[panzerkeil]

It means that there is a referral in the .prs file to a non-existing (or in the wrong format) sound file
open the file mentioned with notepad, and you will find an entry like this:

[samples]
Merlin_XX_Startup.wav

Now check in your samples directory if that file exists
If not: create it (name has to be exactly the same - so Merlin_XX_Startup.wav in this case, or replace the entry in the prs for a sound file that does exist in the samples folder

I have found many wrong entries in prs files; mainly typo's and missing files, and these generated exactly the error you described.

I think everybody using mods should check their logs regularly: I found my game running much smoother after I solved all the issues..