expression help

Hello,

I have a SSRS report that has a data set query with @BegDate and @EndDate.  I'm setting the values like the following:

DECLARE @BegDate Date =  EOMONTH(Dateadd(Year,Datediff(Year,0,getdate())-2,0),11)
DECLARE @EndDate Date =  EOMONTH(Dateadd(Year,Datediff(Year,0,getdate())-1,0),11)

I'm having issue using the following expression.  I believe it's because I'm setting the variables in my query.

"BEG AUM "& MID(Parameters!BegDate.Value,5,2)&"/"&RIGHT(Parameters!BegDate.Value,2)&"/"&LEFT(Parameters!BegDate.Value,4)

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