Within the output from a Poll Agent (under the Info tab for the target element), you may notice a section with the following information:

>>> sadc_cpu

The lock file is currently residing in /tmp and the agent cannot collect data while the lock file is in place
This issue can be resolved by removing the /tmp/uptm_sar.lock file on the target agent. This file is a temporary lock file that the agent uses to ensure it isn't running more than one command at a time and can be safely removed.