SSRS report Visual Studio 2010 multi-select value for IIF

Hi All,
I need to create an SSRS report (RDP, Visual Studio 2010), and one of the parameter (PAR1) is multi-selected (let’s say Val1, Val2 (Val1 and Val2 = are enum)). I have 3 columns in my report (Col1, Col2, Col3).
The problem is that based on the value specified in my PAR1 (for example Val2), the columns Col2 and Col3 should be hidden). Otherwise – visible. If the customer have chosen Val1, Val2 - also all columns should be visible.
I have tried to write an expression in the Column Visibility property for Col2, like =IIF(Join(Parameters!Parameter.Label)<>“Val2EnumValue”,true,false),
I also tried =IIF(Join(Parameters!Parameter.Value)<>“Val2EnumValue”,true,false)
And =IIF(Join(Parameters!Parameter.Label(0))<>“Val2EnumValue”,true,false)
And =IIF(Join(Parameters!Parameter.Value(0))<>“Val2EnumValue”,true,false)
And many other specified here and here
but not succeed.
Any help would be very appreciated.