VBScript syntax

Hi,

I have a problem with this test instruction :

'If valrib = True' returns always 'false'
I tried a lot of different syntax but it don't works
What is the right syntax to evaluate a bollean field ?

My VBScript :

option explicit

'boolean fields
dim valrib   
dim valvitale
dim valcomplet

valrib = PropertyValues.SearchForProperty(1046).TypedValue.DisplayValue
valvitale = PropertyValues.SearchForProperty(1052).TypedValue.DisplayValue

if valrib = True then
Output.SetValue MFDatatypeboolean, -1
else
Output.SetValue MFDatatypeboolean, 0
end if

Thanks for your help

Philippe