I wasn't suggesting that you had screwed up - only looking for clues. Sorry if I caused offence. I'm running out of thoughts now, but here are two -
Take a look and confirm that the exact folder "address" is \Multisamples\72 - REX Drum Loops\Drum n Bass Breaks because I presume that the .progs in question have that coded into them. This is where mine are , and they load without issue into the 214 version of Dim Pro.
Do you have the same problem with Dim Pro running under the microhost?
Edit - Oh, and a third thought. Having got the error, what happens if you click on the Multisample window to invoke the Load Multisample dialogue? Can you force it to load the right multisample, or do you get another error?