First, your use of Dynamic SQL will probably fail. Dynamic SQL is considered a different batch by the execution engine and your local variables will not be in scope. To make it work, you'd have to use the local variable to create a literal within the query:

select  @sql_stat = 'select jeid from jsregistration where username = ' 
SELECT @sql_stat = @sqlstat + '''' + @req_username + ''''

(I broke it into two lines to make the quoting a little clearer. You can do it in one line)

Second. As Sergey mentioned, you really don't have to execute the query to determine the value of the identity that was assigned. Sergey mentioned @@IDENTITY but if you're using SQL Server 2000, I would recommend SCOPE_IDENTITY().

-Mike