1. The problem can be of CIC Mismatch.You can verify the same by giving physical break on the E1 and then verify the CIC values at both end on the E1 which is down at both ends.This will also verify that there is no physical loop on the PCM towards both sides which can also lead to the same problem.
2. If there is no CIC mismatch and no physical loop on PCM, then it can be a problem in definition of SNT.Might be possible that you are creating SNT on wrong SNTP number.
For this you have to find at least on SNT on that RP which is working fine.Then you check its EM number and SNTP.Accordingly decide the SNTP position of new SNT where speech is not through now.
OR
Check the position of DL3 cable in Group Switch and find out SNTP value.