DFF value synchronization in various segments

Hello Experts

I am working on a requirement through Form Personalization on Add Customer Form in which I am passing string on DFF segments to a DB function and getting a string returned to the DFF segments.

When I open the DFF, it shows me the returned value but when I close the DFF it shows me the passed value and not the value returned by the Function.

E.g. I entered '101' in DFF segment and with this as Input to Function; function returns '101 Cambridge Road'. I can see '101 Cambridge Road' when I open the DFF but when I close it shows me '101' only.