Reading input signals

We have instalation with IRB 2400 for ArcWelding. I have defined 501 I/O signals on another aplication with two robots we will have even more signals. I have found next problem:
When I work in RAPID with I/O signals everithing is OK, but when I try to read I/O signals with RAB some of them is not possible to get. I found out that I can get signals on end of eio.cfg file but not signals in begining of eio.cfg file. I also change file and take some signals from begining of eio.cfg file and I put them on end. When the same signal with same declaration was in begining of file I can't get it but when I put signal on end it was OK.