Error in PCU Loopback

Hello Mr/Mrs, I am Suhendy, I am master degree student from university of indonesia I have project to make GPRS private network using OSMOCOM I have trouble in osmo-pcu which my log said like this DLNS ERROR GPRS-NS2-VC(NSE01234-NSVC-UDP-0_0_0_0:23000-127_0_0_1:23000){BLOCKED}: Event RX-RESET_ACK not permitted (gprs_ns2_vc_fsm.c:937) my osmo pcu make loop communication so my osmo-pcu and osmo-sgsn cant connect each other. this is my osmo-pcu.cfg log stderr logging color 1 logging print category-hex 0 logging print category 1 logging timestamp 0 logging print file basename last logging print level 1 ns timer tns-block 10 timer tns-block-retries 3 timer tns-reset 10 timer tns-reset-retries 3 timer tns-test 60 timer tns-alive 5 timer tns-alive-retries 10 pcu flow-control-interval 10 cs 2 alloc-algorithm dynamic alpha 0 gamma 0 Please help me to solve this problem. Thank you