data completeness validation?

Hi excel people, I wonder if someone can give some tips for validating the completeness of my data ... here's my query:

sheet 1 is an input sheet and shows the sales units

sheet 2 is also an input sheet and shows sales prices

sheet 3 is a product of the two and should show calculated income

I say should because if sheet 2 is missing the price then the calculated income will be nil!

Any advice would be greatly appreciated.

Thx

In sheet3 where its calculating the income (sales x price)..

Just replace that formula with an if formula like:

say sales volume = Sheet1!D25
say price = Sheet3!D25

in your sheet3 income sheet:

If (Sheet1!D25> 0, IF (Sheet3!D25 > 0, Sheet1!D25 * Sheet3!D25,"No Price"),"No Volume")

here's an incredibly simplified version (main difference being amount of information and that sheet 1 & 2 also contain formula linked to another workbook.