Please help me€¦..

A B C D E F
Name DateON DateOff DateON DateOff Total Dys

The formula below is working fine but if the E is blank some four digit
numbers is showing.
Is there any way to solve this problem.
Actually I am trying to calculate the days worked between the dates in a
particular year. Some people work 12 time a year some 3 times.

=IF(B2="","",C2-B2+E2-D2+€¦€¦€¦€¦€¦..)

Thanks in advance