Dynamic name of result column in s-proc?

How can I make this stored procedure concept work:

---------------
Create Procedure MyProc @.MyValue varchar(5)
As
Declare @.ColumnName as varchar(11)
Set @.ColumnName = 'Price_' + @.MyValue
Select Sum(Price) As @.ColumnName --??
From MyTable where Item = @.MyValue
Return
---------------

Using @.MyValue = 23 should make the Sum(Price) column name 'Price_23'. It's not working. What am I doing wrong?

BjornUSE Northwind
GO

DECLARE @.ColumnName sysname, @.sql varchar(8000), @.myValue varchar(5)
SELECT @.myValue = '23'
SET @.ColumnName = 'Price_' + @.MyValue
SELECT @.sql = 'SELECT Sum(UnitPrice) As ' + @.ColumnName
+ ' FROM [Order Details] '
+ ' WHERE ProductID = ' + @.MyValue

SELECT @.sql

EXEC(@.sql)|||Thank you thank you!

Bjornsql