Truncate date field

Hello

I have an annexation layer that has Annex_Date field in mm/dd/yyyy format. I am trying to extract just the yyyy part. I have added a new field called Annexation_Year, and I am trying to calculate the records. I have tried to use DatePart and DateYear function for VBScript without any success. Any other suugestions on how this can be handled?

Thanks,
Ruchi Bhutani
GIS Analyst