jup, that was the reason. now i also saw that the windows cmd window was showing an error (copying empty.dum).
so you should check for cards that are 16 MB in size or smaller - these probably will not work.
also, my 4gb card doesnt work as well, though i think cardtricks does manage it to format it in fat16? dont know why it didnt work. anyhow, managed to get a dump using a 2 gb card. thanks!