Report builder expression syntax issue for null (blank) values

Issue resolved by creating a separate calculated field called: "PQDays_Calc", 

and gave it this expression:  =IIf(IsNothing(Fields!PQ_Days.Value),0, Fields!PQ_Days.Value)

Removed the check box for Null values, then, filtered on the new calc field with the original Switch Statements:

Starting:

=
Switch( 
Parameters!IMSCasePQDays.Value = -1, 0, 
Parameters!IMSCasePQDays.Value = 0, 0, 
Parameters!IMSCasePQDays.Value = 1, 31, 
Parameters!IMSCasePQDays.Value = 2, 100, 
Parameters!IMSCasePQDays.Value = 3, 366, 
Parameters!IMSCasePQDays.Value = 4, 731, 
Parameters!IMSCasePQDays.Value = 5, 1096 
)

Ending:

=
Switch(

Parameters!IMSCasePQDays.Value = -1, 36500, 
Parameters!IMSCasePQDays.Value = 0, 30, 
Parameters!IMSCasePQDays.Value = 1, 99, 
Parameters!IMSCasePQDays.Value = 2, 365, 
Parameters!IMSCasePQDays.Value = 3, 730, 
Parameters!IMSCasePQDays.Value = 4, 1095, 
Parameters!IMSCasePQDays.Value = 5, 36500
)

I over complicated the issue initially!