Excel 2007 Difference between 2 dates showing as a negative number

[KJ2607]

Hi I'm having problems with the following formula:

[TABLE="width: 335"]
<tbody>[TR]
[TD]A[/TD]
[TD][/TD]
[TD]B[/TD]
[TD][/TD]
[TD="align: right"]C[/TD]
[/TR]
[TR]
[TD]Date Opened[/TD]
[TD][/TD]
[TD]Date Closed[/TD]
[TD][/TD]
[TD="align: right"]Total days to closeout[/TD]
[/TR]
[TR]
[TD="align: right"]26/07/2013[/TD]
[TD][/TD]
[TD="align: right"]13/08/2013[/TD]
[TD][/TD]
[TD="align: right"]18[/TD]
[/TR]
[TR]
[TD="align: right"]26/07/2013[/TD]
[TD][/TD]
[TD="align: right"]19/08/2013[/TD]
[TD][/TD]
[TD="align: right"]24[/TD]
[/TR]
[TR]
[TD="align: right"]31/07/2013[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]-41486[/TD]
[/TR]
[TR]
[TD="align: right"]01/08/2013[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]-41487[/TD]
[/TR]
</tbody>[/TABLE]

I want to copy the following formula in Column C all the way down: B2-A2 to work out the total amount of days it takes to close an issue out. However until I get a closure date, the formula shows a negative number - which is throwing off my average calculation at the end - any suggestions?

 

[VoG]

Try

=IF(B2="","",B2-A2)

 

[KJ2607]

Thats Great Thanks VoG!!

If I was also looking to create a separate column to actually count he amount of days an issue was open before it was closed off, I had written the following formula:

=IF(ISBLANK (B2), Today()-A2, B2-A2) Which works well so long as I have a start date, However if I don't have a start date, the cell automatically fills in with some random number? Is there anyway to combine what you posted above with my current formula?

 

[VoG]

Try

=IF(OR(A2="",B2=""),"",IF(ISBLANK(B2), TODAY()-A2, B2-A2))

 

[KJ2607]

Wonderful Thanks again VoG!