how to trigger vb script when syncronizing defects from another tool

Hi

Im using a plugin to Jira called JAM to synchronize defectes between Jira and QC.

In QC we have a custom field called 'Detected by Full name (BG_USER_02)

And to that a VB script that upon change of BG_DETECTED_BY runs following vb code

Bug_Fields.Field("BG_USER_02").Value = UserFullName(Bug_Fields.Field("BG_DETECTED_BY").Value)

Works fine when doing work in QC.

But when a defect is synchronized from Jira it seems like the code doesnt trigger.

The code is put in this sub

Sub Bug_FieldChange(FieldName)

is it so that the subs are not triggered when using a synchronization tool?

is there a workaround?

thanks