Problems with my Port

This past Tuesday, was my monthly port flushing. The nurse was able to stick the needle into the port, but the port would not send back any blood. Another nurse, kinda took the needle out, and put it back in, moved it around, but no blood would do anything. One of the nurses put in a dose of a clot buster. Had to sit and wait about 20-30 minutes for it take affect. After than, they were able to get blood, then were able to flush it. Whenever my port is flushed, I am given a dose of heperin. This was the first time, this has happened with my port.