Failure<"Unable to find DIALOG.TLK">
How do I fix this and what am I doing wrong?
Well, the error message should tell you pretty much what's wrong... in case you fail to know, you need to unpack the mod to the game folder, not to a subfolder...
So say you want to install the iiSpellSystemAdjustments(v7.1).zip mod, you unpack that directly to the
BG2 game folder where the dialog.tlk file also exists, after the unpacking you have the Setup-iiSpellSystemAdjustments.exe file and the iiSpellSystemAdjustments folder in there, then you just run the .exe and it will find the required file...