[AccessD] A2K: Not Adding up

Hello all
I have a table (tblAwards) that has 2 fields
1st called ElectiveHours data type = number/Long Integer (Say it has a value of 5)
2nd called CompulsoryHours data type = number/Long Integer (Say it has a value of 100)

I have a form with a combo bound to tblAwards
So MyCombo.Column(0) is bound to ElectiveHours and MyCombo.Column(1) is bound to CompulsoryHours.

I have a control on the form that has the following as its ControSource
MyCombo.Column(0) + MyCombo.Column(1). So 5 + 100 should = 105

But I keep getting the concatenated answer version 5100

What am I doing wrong?

Many thanks in advance

Darren