LTE IRAT Handover Preparation are Failure

[lihanbok]

Dear Experts,
I have problem with LTE IRAT HandoverPreparationFailure ( Picture below)IRAT failure.jpg
HandoverRequired informations are correct. But LTE IRAT Handover Preparation are Failure( Unknown Target ID code).
Could you please tell me how to solve this problems.
Thank you so much.
Best Regards,
LIhanbok

[Shakeel_15]

First Check External definitions like TAC,PCI,ARFCN etc should be ok
Secondly check the no SCTP links of problemtic site and enighbors
Also S1 Interface count should also be same on problematic site and neighboring area depends on MME pools