Problem with nested iif

Hi,

I am trying to produce the correct results to pick up a phone number.

If the telephone has a value, then show this number, if the telephone does not have a number then use the Home-Tel.

If the Home-tel has a number then use the Mobile number.

My expression below does not pick up all the numbers, and i think it may be because sometimes two of the numbers have values.

=IIF(Fields!Telephone.Value > 0, Fields!Telephone.Value, IIF(Fields!Home_Tel.Value > 0, 
Fields!Home_Tel.Value, Fields!Mobile.Value))

Can someone help please?

M Stoker