Request denied by nimsh

Hello, i try to configure NIM master & client and backup couple of boxes to master nim server.
I have successfully setup for the NIM environment both for client and server (i think), but when i try to make mksyb image i get this message:

0042-001 nim: processing error encountered on "master":
   0042-006 m_mkbosi: (From_Master) connect Error 0

0042-008 nimsh: Request denied - sebsapp1.sofiyskavoda.local

The command what i use is:

nim -o define -t mksysb -a mk_image=yes -a mksysb_flags=e -a server=master -a location=/export/nim/mksysb -a source=ERPDEV ERPDEV_mksysb

Can somebody help me?
Thanks

Please check that ports 3901 and 3902 are open on any firewall / router that might be between the NIM server and the NIM client.

I get this error sometimes after doing a Live Partition Mobility. I've seen it other times too and I'm not sure exactly what causes it, but I am able to fix it by doing this. Go into the NIM server and remove the NIM machine.

smitty nim --> Perform NIM Administration Tasks -->
Manage Machines --> Remove a Machine

It will probably error off about not being able to remove the /etc/niminfo off the client. Disregard that. After the NIM machine definition has been removed, login to the NIM client itself and re-configure it as a NIM client:

rm /etc/niminfo
smitty nim --> Configure Network Installation Management Client Fileset

Fill out the required fields and then try your NIM commands again. This fixes it for me.