I have a keymap for my keyboard, that contains several mathematical symbols etc. it works great with notepad and other unicode-able programs, but if i type the symbols in mIRC it shows them as ? or as a letter looking almost like that sign (a instead of alpha etc.). If i paste the symbols from notepad everything works fine, it's just the direct typing, that doesn't work and i have no idea why, any suggestions?

It's probably because you're not using a font that contains those symbols. mIRC doesn't support font substitution at the moment.

Not sure if that will help, try to activate the option from Options->Irc->Messages->Multibyte editbox ?

Well, the problem is not my font (I'm using Fixedsys Excelsior which has all my needed characters in it) and notepad when setting the same font shows exactly the signs i asigned to the key-combination. i can copy'n'paste them and they go fine in the editbox and are sent correct, but when typing them directly in the editbox using the same key-combinations, it only shows similar symbols from ascii like a for alpha or ? for special chars. And yes, my Multibyte Editbox is enabled in the Options. I would really appreciate if anybody knew a solution to this problem.