I/O assignments to LPARs

Hello everyone.

I am a long time IBM i user, who is new to HMC managed LPARS.

I have inherited a good sized 9406-525. I now have it set up and running, and it works pretty well.

My problem is that of the 3 LPARs set up, only one will start.

The other 2 can't seem to find their load source.
I am attempting to IPL them into DST, to try and diagnose the problem, but the alternate load source is a
shared resource, and I can't seem to access the tool needed to assign it to the LPAR.

I have a copy of iNav running on my desktop, and when I attempt to access the "Logical Partitions" option ,
under "Configuration and Service", I get a popup that says
"User null needs logical partition or administration privileges to perform this action"

When the DST login pops up, I sign on as QSECOFR, so authority should not be an issue.
What I don't get is what user "null" is supposed to be.

Does anyone here know how to set up user "null" in the SST user database?

Or, is there another method of assigning the I/O to an LPAR, either HMC or green screen?

We are a heavily legacy environment, and this box s long off maintenance, so IBM support is not readily available.

I welcome suggestions.

Thanks!

Armand Borick