Print chars on screen in 40 col and 80 col mode different?

Hi!

My Q is simple but don't know if have simple solution.

I'm using routine $C00C to output character in A (Accumulator) to screen - it's BASIC proutine.
Char is printed correctly in 40 column mode, but prints nothing is 80 column mode...
So, it's different, I think.
I know that access of VIC and VDC is totally different, but this routine only outputs character in A to screen - so why works in 40 / works not in 80 column mode?
I used also KERNAL routine $FFD2 with the same result.

So, how to print characters on 80 column screen?

Thanks for every reply.

Miro