Set analysis

[risabhroy_03]

I want to convert my below statement in set analysis

if([Invoice_Date_GMT_Updated]=date(max(total <[Company_Code]> [Invoice_Date_GMT_Updated])),

sum(Quantity),

null()

)

I wrote this 

Sum({<[Invoice_Date_GMT_Updated]={'=floor(num(date(max(total <[Company_Code]> [Invoice_Date_GMT_Updated]))))'}>}Quantity)

But extra rows are also coming.

Please help.