Using VB.net to alter Stored Parameters - asp.net

Question

I am having an issue modifying a stored procedure variable with VB.net. I have found many posts on the topic that made it seem like a simple .AddWithValue solution but I keep ending up with a the following exception:
The IListSource does not contain any data sources.
The stored procedure is a Dynamic Pivot table that works great with a static value for #dcs
CREATE PROCEDURE [dbo].[dcspull]
as
DECLARE #cols AS NVARCHAR(MAX),
#colsNull AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX),
#dcs AS INT
select #cols = STUFF((SELECT ',' + QUOTENAME(FirstName)
FROM[Training Data]
WHERE DataCenterID = #dcs
GROUP by FirstName
ORDER by FirstName
FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'),1,1,'')
select #colsNull = STUFF((SELECT ', coalesce(' + QUOTENAME(FirstName)+''''')
AS '+QUOTENAME(+FirstName)
FROM [Training Data]
WHERE DataCenterID = #dcs
GROUP by FirstName
ORDER by FirstName
FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'),1,1,'')
set #query = 'SELECT Topic, ' + #colsNull + '
FROM
(SELECT FirstName, Topic, Level
FROM [Training Data]) x
PIVOT
(MAX(Level)
FOR FirstName IN (' + #cols + ')) p'
execute(#query)
The only value I am trying to change via VB.Net is #dcs. When #dcs is set statically the Gridview populates as expected, but as soon as I try to pass a value to the parameter it breaks.
Dim SQLCon As String = ConfigurationManager.ConnectionStrings("tCString").ToString
Dim DBConnSQL As New SqlConnection(SQLCon)
Dim da As New SqlDataAdapter
Dim ds As New DataSet
DBConnSQL.Open()
Dim dbcheckone As New SqlCommand("dcspull", DBConnSQL)
dbcheckone.parameters.addwithvalue("#dcs", Convert.ToInt64(DropDownList1.Text))
da.SelectCommand = dbcheckone
da.Fill(ds)
GridView1.DataSource = ds
GridView1.DataBind()
I am fairly new to stored procedures and am assuming this is something I just don't understand about the relationship.

Answer 1

First, I don't see any parameters in your stored procedure. They should come before AS.
Sample Create SP:
CREATE PROCEDURE HumanResources.uspGetEmployeesTest2
#LastName nvarchar(50),
#FirstName nvarchar(50)
AS
Now, when you add those parameters it should work under these conditions:
You need to set command Type
dbcheckone.CommandType = CommandType.StoredProcedure
Even though you don't use other parameters during your call, your procedure signature and procedure itself don't match. You can't omit non-optional parameters. So you need to list every parameter
dbcheckone.parameters.addwithvalue("#cols"...
dbcheckone.parameters.addwithvalue("#colsNull"...
dbcheckone.parameters.addwithvalue("#query"...
dbcheckone.parameters.addwithvalue("#dcs", Convert.ToInt32(DropDownList1.Text))
About the last line here - you set it in your code to Convert.ToInt64 but your parameter is int, therefore it should match int32.