I recently had the need to deploy IBM Client Access 6.1 on a Citrix XenApp 6.5 farm, everything was fine for the first month or so and then users started getting the error "PC5250 License Error CWB0999 Unexpected error: unexpected return code 9052 274d"
After a lot of digging I narrowed down the problem to the reg key HKLM\Software\Wow6432Node\IBM\Client Access\Common\Global System Information\
There needs to be a key for each iSeries server that the users will connect to (In my case PROD, TEST and DEV) and under each server key there is a key titled "License Management".
For some reason when in a Citrix season (I have not tried RDP) the server keys do not get created and and the REG_BINAARY value "Date system last checked for nomax" under "License Management" does not get updated.
If the "Date system last checked for nomax" REG_BINAARY value is not updated every 30 days or so the registry information for that iSeries connection is removed and the next Citrix user to start a Client Access connection to that server is given the above license error.
It does not seem to be permissions related in my cause even creating a new iSeries connection within a Citrix session as an administrator does not update "Date system last checked for nomax" you have to be on the Server console.
To me it seems like a bug in Client Access 6.1 running on a remote desktop connection.
While troubleshooting the issue with Sys Internals Process Monitor I notices Client Access checks in the registry for "Number of days to wait for next nomax check"
This does not exist in the registry by default so I created "HKLM\Software\Wow6432Node\IBM\Client Access\CurrentVersion\Common\License Management\Number of days to wait for next nomax check" on each Citrix server and set to it to 9999 which is about 27 years.
After that I connected local to each of the Citrix Servers and created the required connection with Client Access so the iSeries servers where added to the registry.
One thing to watch out for is that the users Client Access connection profiles need to use the same server name as what is in the registry, if you example their connection uses the IP address then you will either need to change the users connection to use the name or also create a connection local on the Citrix servers using the IP address so the required registry information gets created.