I have to say that I programmed another, similar board succesfully. So I think its not the boardlayout or so..
From the Miniprog3 user manual -
okay, thanks Dana. I think I found something. On my board I've connected Pin1 for XRES, that dosent work (even I've checked the option in the system window). After soldering a wire to XRES it worked...
You are always welcome!