Facing issue while Requesting Build from RTCz getting RJZZ0717E Cannot query system definition because Failed to run the query. Can any one help me ?

Here is the description about issue:
System Info:
RTC for System z v 4.0.2
Build Agent - z/OS Dependency Rational Build Agent

Description : While requesting build, I am getting failure message
"CRJZZ0717E Cannot query system definition because Failed to run the query. Response Status Line:
HTTP/1.1 503 Service Unavailable
    at com.ibm.rational.buildforge.buildagent.internal.service.BuildAgentRequestService.invokeBuildParticipants(BuildAgentRequestService.java:923)
    at com.ibm.rational.buildforge.buildagent.internal.service.BuildAgentRequestService.invokeParticipants(BuildAgentRequestService.java:898)
    at com.ibm.rational.buildforge.buildagent.internal.service.BuildAgentRequestService.runBuild(BuildAgentRequestService.java:225)

Same way When i do Update stream on Source Code data - also facing same error message.

Can any one help?

Thanks - Viji