Does anyone have experience getting a Linux CPAS server to authenticate against Microsoft AD?

I've set up the LDAP parameters as follows:
LDAP Servers: ldap://xxx.xx.xx.xx:636
LDAP Domain: nih.gov
LDAP Principal Template: ${email}   
Use SASL Authentication: No

When I click on 'Test LDAP server', the browser window shows:
500: Unexpected server error
156.40.70.10:636; socket closed

In the labkey.log file I see:
----------------------------------
ERROR ExceptionUtil 2008-04-18 14:24:46,431 8443-Processor23 : Unhandled exception caught in Global.app: 500: Unexpected server error
javax.naming.ServiceUnavailableException: 156.40.70.10:636; socket closed
        at com.sun.jndi.ldap.Connection.readReply(Connection.java:416)
        at com.sun.jndi.ldap.LdapClient.ldapBind(LdapClient.java:340)
        at com.sun.jndi.ldap.LdapClient.authenticate(LdapClient.java:192)
        at com.sun.jndi.ldap.LdapCtx.connect(LdapCtx.java:2658)
        at com.sun.jndi.ldap.LdapCtx.<init>(LdapCtx.java:287)
        at com.sun.jndi.ldap.LdapCtxFactory.getUsingURL(LdapCtxFactory.java:175)
        at com.sun.jndi.ldap.LdapCtxFactory.getUsingURLs(LdapCtxFactory.java:193)
        at com.sun.jndi.ldap.LdapCtxFactory.getLdapCtxInstance(LdapCtxFactory.java:136)
        at com.sun.jndi.ldap.LdapCtxFactory.getInitialContext(LdapCtxFactory.java:66)
        at javax.naming.spi.NamingManager.getInitialContext(NamingManager.java:667)
        at javax.naming.InitialContext.getDefaultInitCtx(InitialContext.java:288)
        at javax.naming.InitialContext.init(InitialContext.java:223)
        at javax.naming.InitialContext.<init>(InitialContext.java:197)
        at javax.naming.directory.InitialDirContext.<init>(InitialDirContext.java:82)
        at org.labkey.api.security.SecurityManager.LDAPConnect(SecurityManager.java:439)
        at org.labkey.core.admin.AdminController.testLdap(AdminController.java:359)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.beehive.netui.pageflow.FlowController.invokeActionMethod(FlowController.java:815)
        at org.apache.beehive.netui.pageflow.FlowController.getActionMethodForward(FlowController.java:754)
        at org.apache.beehive.netui.pageflow.FlowController.internalExecute(FlowController.java:428)
        at org.apache.beehive.netui.pageflow.PageFlowController.internalExecute(PageFlowController.java:285)
        at org.apache.beehive.netui.pageflow.FlowController.execute(FlowController.java:308)
        at org.apache.beehive.netui.pageflow.internal.FlowControllerAction.execute(FlowControllerAction.java:48)
        at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)
        at org.apache.beehive.netui.pageflow.PageFlowRequestProcessor.access$201(PageFlowRequestProcessor.java:106)
        at org.apache.beehive.netui.pageflow.PageFlowRequestProcessor$ActionRunner.execute(PageFlowRequestProcessor.java:2049)
        at org.apache.beehive.netui.pageflow.interceptor.action.internal.ActionInterceptors.wrapAction(ActionInterceptors.java:90)
        at org.apache.beehive.netui.pageflow.PageFlowRequestProcessor.processActionPerform(PageFlowRequestProcessor.java:2120)
        at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
        at org.apache.beehive.netui.pageflow.PageFlowRequestProcessor.processInternal(PageFlowRequestProcessor.java:601)
        at org.apache.beehive.netui.pageflow.PageFlowRequestProcessor.process(PageFlowRequestProcessor.java:887)
        at org.apache.beehive.netui.pageflow.AutoRegisterActionServlet.process(AutoRegisterActionServlet.java:611)
        at org.apache.beehive.netui.pageflow.PageFlowActionServlet.process(PageFlowActionServlet.java:157)
        at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
        at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:679)
        at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:461)
        at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:399)
        at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:301)
        at org.labkey.api.view.ViewServlet.dispatchBeehive(ViewServlet.java:235)
        at org.labkey.api.view.ViewServlet.service(ViewServlet.java:140)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
        at org.labkey.api.data.TransactionFilter.doFilter(TransactionFilter.java:36)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
        at org.labkey.core.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:124)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
        at org.labkey.api.module.ModuleLoader.doFilter(ModuleLoader.java:888)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
        at org.labkey.api.security.AuthFilter.doFilter(AuthFilter.java:82)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:525)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
        at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
        at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
        at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
        at java.lang.Thread.run(Thread.java:619)

-----------

Any suggestions?