Eliminate #Value in Time Diff Calculation

[Phishdawg]

How can I write the formula to account for blanks in the 'OutTime' column and eliminate the #VALUE! content?

I'd be fine if the formula said - if F2 blank use D2 content in calculation, which would return a 'WaitTime of 0:00:00.

[#2]

@Phishdawg 

I'd use

=IF(OR(D2="", F2=""), "", F2-D2)

or

=IF(OR(D2="", F2=""), 0, F2-D2)

and format the cells with the formula as h:mm:ss