Thanks again,
I tried and switched to jrxml but found that my subreports are not loaded.
Since I needed to get over this fast I did not bother to investigate further and installed the complete Jasperstudio 6.5.1.
Still if anybody has an Idea why my jrxml subreports don't get loaded I'd be happy to know.
Although my reports do work again I am not really happy because I am used to having the Java IDE, DBeaver and Jasperstudio integrated within a single Eclipse installation.
Does anybody know where to find the Jasperstudio 6.5.1 eclipse Plugin? It looks like it is not available anymore.
Andreas