This message indicates that eMake failed to acquire agents from the Cluster Manager, so eMake is unable to continue executing the build. eMake will wait in this state until agents are made available to it. This warning does not indicate a build failure, but it does mean that the build will take longer to complete than normally expected.
Fundamentally this message means that there are not enough enabled agents to service all currently running builds. Other builds are using all the available agents, leaving none for this build.
Note that if you have enabled a Resource Manager in the Cluster Manager, and you have specified a resource for this build, then this message means that there are not enough enabled agents matching the resource specification. There may be unused, enabled agents on the Cluster Manager, but not part of the resource specified for this build.
Check that the Cluster Manager has enough agents available to service the currently running builds. If not, you can add agents to the cluster, or use max agent and build priority settings to limit the number of agents any single build can use, in order to make room for other concurrent builds.
If you are using resources, you should also make sure that you have specified the resource correctly. If the specification is correct, check the resource definition in the Cluster Manager (if you are using the built-in Resource Manager) to ensure it includes all the agents you intend it to include. If you are using an external Resource Manager such as LSF, check that the external resource manager is configured correctly for the resource you have specified.