Sure that you are using the right driver? There used to be a project called "Graffity" that never saw the light of day, but was supported by some programs. It was planned to be a Zorro graphics card, and it was NOT an iComp product.
Make sure that it's the "Graffiti" driver, with an "i" at the end, make sure to use PAL and set the X-offset for both text and graphics to a number that is a whole-number-multiple of 8.
Jens