Need help getting an overlay to display properly

I am brand new to SimHub and have been creating an overlay of different lap times.  It all is working as it should except for the last lap to best lap delta.  I have what appears to be the correct formula as I am getting a valid delta time displayed in the RAW RESULT field but the actual overlay displays "mm.ss.fff" rather than what is in the RAW RESULT field.  How do I get the overlay to display the actual time delta data that is displayed in the RAW RESULT field?