Don't know exactly. It may depend on your environment. As a portmapper runs by default on a UNIX machine, i guess you talk about Windows.
In this case, make sure that nsrexecd is running. In very rare reasons it might be that the embedded portmapper interferes with another one loaded by another software vendor. Also look at the Event Logger for problems pointing in that direction.
If on UNIX/Linux the same applies in principle, although rpcbind is the OS' portmapper: make sure that you see 2 dependent nsrexecd processes.