In the thread, Re: Macro substitution in sql views no longer possible Thread #975746 Message #976496
the following quote appears:
"I thought '&?' makes it clearer, when you see the SQL, that the variable is a parameter. I also like that in VFP9 you must define the variable before you can create a view, or else you get an error."
When I run the Sql now using the &?vp_filter

   AND &?vp_filter ;

I get the following error: "Missing operand".

Is this due to the fact that I have not defined the variable?
I define it in the parm list of the view:

parm_list=parm_list+"vp_Gender,'C';vp_ParFirst,'C';vp_ParLast,'C';vp_filter,'C'"

But is there something else I am missing?
On the Search button of the business object form, I am defining a private vp_filter.