help with NIM backup error

Hello all....
I am trying to backup a client from the NIM master. While doing so, I get this error:

backup: 0511-089
can not open /tmp/6282.mnt0/<hostname>_mksysb_<date>
0042-001 m_mkbosi: processing error encountered on client
0042-001 m_mkbosi: processing error encountered on master
0042-154 c_stat: the file or directory /export/nim/mksysb/<hostname.date> does not exist.

any suggestions appreciated.