Internal generated number not getting replaced after CR final check approved in Custom data model

We have created a custom data model with Reuse mode. Assigned internal number range object to type 1 entity for temporary number.

I have implemented the code to map with generated actual number with temporary internal number range in SAVE method. After activation, CR is getting final check approved but the new generated internal number is not getting replaced with temporary number on CR screen. Can any body help me on this issue.