LB7 ECU will not read

Hi,
I have done a Engine swap in an GMC Yukon XL from a 8.1L to a 2004 Duramax. The only problem now is that when I try to read out the ECM IT says time out and When I try to do a read entire I Get the message Unlocker:x35 Invalid key. I have bought a used ECM and the same happend With that. Is IT something With my MPVi2 that is wrong? Or what is going no here? I tred to read the 8.1L ECM and that worked just fine.

Regards
Fredrik B?hle
BG Racing, NORWAY

Same thing happened to me. But I was trying to read an already tuned ECM. Your problem might be that it is already Tuned by a different program.