BRF+ - Number to timepoint conversion

Hi all,

I need to calculate the difference in days between two timestamps.

These timestamps are from table GRFNMWRTINST and are appearing as 'Number' data elements instead of 'Timepoint' data elements in BRF+.

So, when I try to use the function DT_DURATION_DIFF_INT_DAYS, I get the following error message:

"Incorrect parameter type Number supplied for function DT_DURATION_DIFF_INT_DAYS, expected type timepoint.

Is there a function to convert number to timepoint ? (I couldn't find a suitable one.) If not, what is the simplest way to calculate the difference in days between the two timestamps.