What am I doing wrong?? Timing cover/post cam install

Timming covers are aluminum and subject to distorting. Lay it on something flat like a piece of glass and you might find the larger bolt holes around the perimiter are holding the small upper edge away from your block. A 220 grit sand paper will produce about the right surface finish. Some sand mating parts too smooth. A very fine wet sand would only allow the gasket to slide.