Hi,
thank's for the advice. I haven't been able to work with the code for a while and today, when trying to get my head around the memset function you mentioned, the problem turned out to be not in the detection but in some of the feedback voids I've created. Some of them send to much data to the port, apparently, creating an overload that crashes the reading tags function. When cutting that code down it works!
Thank's anyway 
I think the memset to clear arrays might come handy if I increase the number of tags in the future.
Best Wishes and thanks again..
Sara