Delete presence of a User on ZKTeco F18

Question

I want to delete the presence (date and time of entry/exit) of an employee from the ZKTeco F18 time clock

so I put the following code:

Ok =zKemKeeper>>ClearData(MachineNumber,1)

if ok=true then
  info("successfully")
endif

My code works well for the K14 but for the F18 does not erase the presence even if the boolean variable is true

Thank you for giving me a lead.