Argument not specified for parameter error.(IIF) Report Builder 3.0

Question

Hi, Im trying to set the font colour of text dynamically dependant upon the date. 
This is using report builder 3.0 expressions. -I'm new to using expressions. 
I want my expression to do this:
If less than or equal to today, RED, 
If greater than today but less than today+30 days, yellow, (this is the confusing bit)
else Black.
My expression is this:
=IIF(Fields!Standard_Licence_Expiry.Value =< TODAY(),"Red",
IIF(Fields!Standard_Licence_Expiry.Value BETWEEN TODAY() and (DATEADD(DateInterval.DAY,30,GETDATE())),"Purple","Black")
However I keep getting the error:
The Color expression for the textrun ‘Standard_Licence_Expiry.Paragraphs[0].TextRuns[0]’ contains an error: [BC30455] Argument not specified for parameter 'FalsePart' of 'Public Function IIf(Expression As Boolean, TruePart As Object, FalsePart As Object)
As Object'.

Answer 1

Hi BlakeWills,
Unlike T-SQL, there is no BETWEEN keyword in
SSRS expressions. So we can try the expression like below to achieve your requirement:
=IIF(Fields!Standard_Licence_Expiry.Value <=TODAY(),"Red", IIF(Fields!Standard_Licence_Expiry.Value > TODAY() and Fields!Standard_Licence_Expiry.Value < DateAdd(DateInterval.Day,30,Today()),"Yellow","Black"))
Please note that the Standard_Licence_Expiry field should be a date type data in the expression above. If it is a string type, we should use the expression below to replace the Fields!Standard_Licence_Expiry.Value:
cdate(Fields!Standard_Licence_Expiry.Value)
If there are any other questions, please feel free to ask.
Thanks,
Katherine Xiong
Katherine Xiong
TechNet Community Support