The SQL Server .NET Data Provider does not support the question mark (?) placeholder for passing parameters to a SQL Statement or a stored procedure called by a Command of CommandType.Text. In this case, named parameters must be used.

The OLE DB .NET Provider does not support named parameters for passing parameters to a SQL Statement or a stored procedure called by an OleDbCommand when CommandType is set to Text. In this case, the question mark (?) placeholder must be used.