Date time picker

Question

I use timespan and datetime pickers in my project, it calculates correctly for todays time for eg.,(dtpouttime-dtpintime), but in case if there is shift which starts today
and ends the next day and probably that may even extend to one more day(If the employee works over time ).I am finding difficulty in calculating this, cam any one help me ,how to calclate this thing.

Thanks in Advance,
A.Durga Prasad