N26 question: send gtpv2 request to spirent`s mme, spirent`s service get internal error , and no pcap return.

I test N26 transfer ran into trouble.

I(AMF) send gtpv2 request(Forward Relocation Request) to Spirent`s mme, but mme not return reponese information. and when case ending, no pcap package return.
May be the gtpv2 request`s IE not meet expectations cause spirent`s service internal error and down.

I have debug log and tac report.