[Serusers] LCR module, ser0.9.6

I am using LCR module and I have two set of gateways (group id 1 and group id 2). I have defined a list of prefixes and the corresponding gateway group id's. All is working fine vis-à-vis the prefixes and the choice of the gateway group. My problem is that if a RURI is supposed to be handled by gateways in group id 1, and all the gateways in that group are busy, the call then gets forwarded to the gateways in group id 2 although the prefix does not match to the one associated with group id 2. Is there any way to disable this so that if all gateways are busy in group id 1, SER does not forward calls to the group id 2? Thanks in advance