Please make sure that both ends of the C8 cable are connected to the SR5500 channel 2-out port & SR5038's P4 port. Please also refer to the attached A304 Rack setup guide.
The SR5500 Channel 2-out port is used for fading and setting power levels of the GSM cell.
The C8 cable not being connected typically happens when users forget to re cable the A304 rack, after having run Data Throughput tests with RxDiversity.
If the UE still will not camp on the 2G cell, please verify technology settings on the UE and use of the proper 64K UICC E (or F) SIM card (programmed with GSM-BTR-1-DAM PCOM script)