RosBE brings up compile errors, after updating the svn code several times

I'm using RosBE under Ubuntu Linux Lycid Lynx 10.04 and when I do svn update (the svn from the ubuntu repositories) RosBE can't compile the code properly anymore. There are some compiler-errors. After I do a clean and a makex clean it often works again. How can that be? This might have something to do with some misstakes in a makefile whatsoever. (just a wild guess)