.NET - "Specified cast is not valid" error when instantiating oleDBCommand

Specified cast is not valid.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidCastException: Specified cast is not valid.

Source Error:

Line 12:         Public Sub AddCart(ByVal CustomerID As Integer, ByVal ProductID As Integer, ByVal Qty As Double)
Line 13:             'Add a single row item to the cart
Line 14:             Dim objCmd As New OleDbCommand("uspAddCart", objConn)
Line 15:             objCmd.CommandType = CommandType.StoredProcedure
Line 16:

The error refers to line 14. At one stage this was working. Now all of a sudden it's not! And all functions containing code like line 14 now fail the same way. Any ideas please?
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dfu23Connect With a Mentor Commented:
objConn needs to be an OleDbConnection ... it appears that you are setting it as a string from the code snippet above ...

I think that it should be something along the lines of the following (I use C# more than VB.NET so this might be a little off):

Dim objConn As New OleDbConnection(CType(configurationAppSettings.GetValue("DSN", GetType(System.String)), String))

This will set the variable objConn to the OleDbConnection type and will pass it the connection string from your web.config file for the constructor. There should not be a need for the second line of code:

Dim strConnectionString = "Provider=Microsoft.Jet.OleDB.4.0;Data Source=C:\Files\vsDotNet\ProvidenceVineyard\database\ProvidenceData.mdb"

Which duplicates the value in the key that you have in your web.config and would defeat the purpose of having it in there.
stupid question: the variable objConn is of type OleDbConnection, right?
I bet that is it.
ravlAuthor Commented:
The problem is certainly with obConn. I am using:
        Private objConn = CType(configurationAppSettings.GetValue("DSN", GetType(System.String)), String)
        Dim strConnectionString = "Provider=Microsoft.Jet.OleDB.4.0;Data Source=C:\Files\vsDotNet\ProvidenceVineyard\database\ProvidenceData.mdb"

and DSN is defined in webconfig <appsettings> as:
            <add key="DSN" value="Provider=Microsoft.Jet.OleDB.4.0;Data Source=C:\Files\vsDotNet\Test\database\ProvidenceData.mdb" />
WHat am I missing?
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