I've recently started re-playing the Forgotten Realms Pools series and it's the first time I'm using GBC. Since I've already finished most games the original way twice, I have to admit that I couldn't resist a little 'adjusting' this time and so I created a party including 4 multi-classed characters that I edited to humans right after creation in order to avoid the other races' level caps.

After finishing PoR I transferred the characters to CotAB. The issue that i'm having now ist that while memorizing spells in camp is working fine, none of my magic-user characters are actually able to cast any spells in combat (when I press "C" the screen goes gray for a moment and then back to the combat window, where the active character is still awaiting my instructions). Note that all of my MU characters are human-turned multi-class characters:
1 fighter/magic-user
1 fighter/magic-user/thief
1 cleric/fighter/magic-user (cleric spells work just fine for him)

BTW, For transferring I didn't use copycurs.exe because it didn't work on my x64 DOS prompt so I simply copied the necessary files from PoR into my CotAB directory (at least that's what I thought I did). Maybe I also made a mistake there.

Has this occured to anyone else?

Any hints would be much appreciated since I don't wanna have to drop my beloved party :(

Thanks!