Make it mandatory to fill a cell- before tabbing to next cell

[derek.hughes]

I have a worksheet that is protected and users can only tab through and select unlocked cells. I am aware I can make cells mandatory on save/close, etc. using a macro, but is there a way I can prompt the end user before they tab to the next cell?

I am envisioning a data validation box popping-up if they try to tab forward and leave the cell blank. Any ideas? Is there a formula I could type into the custom validation box?

Much appreciated!

 

[derek.hughes]

SOLVED.

I figured out a workaround. I put a validation on the NEXT cell in the sequence. (e.g. if I was on D3 and hit tab and it took me to D4)

Using that example for reference, I set a custom validation on D4 to say - ISBLANK(D3) and a message that they could not enter D4 until they went back and entered D3.