Suppress or Hide Previous Value in SSRS 2008

Hi Friends,

I have a requirement where i have to suppress previous value if that is equal to next or last value...

i have tried using below expression in Test box visibility but  this is suppressing whole value.

=IIF(Sum(Fields!AnnualFees.Value)=Last(Sum(Fields!AnnualFees.Value)),True,False) 

as a second option i have tried below code in Text box expression instead o Visibility..

=IIF((Sum(Fields!AnnualFees.Value))=Last(Sum(Fields!AnnualFees.Value)),Sum(Fields!AnnualFees.Value,"StudentID"),Nothing)

but it is not working...Please help me..

Thanks,

Sam.