I had the same problem - I went up one level, dropped the items there, collected them again, went down to the summoning level again and voilá - it worked out. <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />
Don't know if you tried that already, but you didn't say *where* you dropped the stuff - it did not work for me to just drop it in the summoning room, I guess you have to be a bit away from the place or so. Hope that helps! <img src="/ubbthreads/images/graemlins/wave.gif" alt="" />
