Package failed due to parameter named "SomeParameter" which is not found in the parameter mapping

I am creating SSIS Package using the stored procedure with 3 input parameters passing into the stored procedure as my source.
My destination eventually will be Excel file.  But before I worry about my destination, I want to get my source of data working.

In my SSIS Package and In my Data Flow,
I have OLE DB Source
Under OLE DB Source Editor,
Data access mode is SQL Command
SQL Command Text is EXEC spNameOfMyStoredProcedure ?,?,?

In my Parameters button,
I have Parameters
0 User::Processdate Input
1 User::BeginDate Input
2 User::EndDate Input


I have created Variable Name User::Processdate
I have created Variable Name User::BeginDate
I have created Variable Name User::EndDate

When I executed the SSIS package, I received the following error:

I thought I had my parameters mapped in the Parameters button in Connection Manager.

Thank you in advance for your help.