Question about null value

[#1]

Dear All,

It's me again..

I recently have the expression:

=if(Len(Vipmail)=0,'No','Yes')

In database there are some vips have not input mail address,

I got the Listbox having 2 Rows finally, buy for the 'No' field,

it's always in grey color

Does anyone have any idea?

Many Thanks

Calvin Lin