The worker is unable to mount the network drives or access the shares via UNC. Are you running the worker in service mode or desktop user mode? And are you using a proxy user, and does that proxy user have permissions to mount or access network shares?
As a test, take a note of the drives you have mapped on your local workstation with the "net use" command. Then submit a job to your farm that also runs "net use". Compare the output of this command when run locally and on the worker.