How to validate 2 fields

I have a transaction table, There are 2 fields FuelLiters & FuelAmount. Both should be >0 or =0. If by mistaken FuelLiters entered as 0 and FuelAmount >0, computer should prompt about this mistake.

Abdul30dec80 pointsBadges:

Restricting the user to insert next record

Hai all, I have a subform which is in datasheetview mode , I have to validate the subform field s in such a way that if one of the fields is empty i will popup a msg like 'must enter a value ' then the focus should goto that field and restrict the user to insert next record till the user provides...

Giridharrajup5 pointsBadges: