How to apply the parameter in the first dataset???

This is what I tried.

SELECT * FROM

(SELECT DISTINCT

a.DiseId,

n1.LastName,

n1.FirstName,

n1.MiddleName,

...............................

FROM Table1 a

----------) AS Entity

WHERE Entity.FirstName + ' ' + lastName = @FullNameParam

When I created this query. "Define Query Parameters" window was displaying for the @FullNameParam.

I removed a "Order By" from the original query but still no data was showing in the table.