Error in Stored Procedure

I'm getting the following error in the stored procedure below "Object must implement IConvertible". Can anyone see why?

   Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click

        If Not ValidateProgrammeFields() Then Exit Sub

        'Check the status of the connection
        CheckConnectionStatus()

        Dim cmd As SqlCommand = cnn.CreateCommand

        Try
            cmd.CommandType = CommandType.StoredProcedure
            cmd.CommandText = "procInsertProgrammes"

            cmd.Parameters.Add(New SqlParameter("@UserCreated", SqlDbType.Text, 35))
            cmd.Parameters("@UserCreated").Value = g_Username
            cmd.Parameters.Add(New SqlParameter("@DateCreated", SqlDbType.DateTime, 40))
            cmd.Parameters("@DateCreated").Value = New Date(Today.Year, Today.Month, Today.Day)
            cmd.Parameters.Add(New SqlParameter("@JobClubNumber", SqlDbType.Text, 100))
            cmd.Parameters("@JobClubNumber").Value = txt_JobClubNumber.Text.Replace("'", "''")
            cmd.Parameters.Add(New SqlParameter("@JobClubNumberSeries", SqlDbType.Int))
            cmd.Parameters("@JobClubNumberSeries").Value = ComboBox_FinancialYear
            cmd.Parameters.Add(New SqlParameter("@StartDate", SqlDbType.DateTime, 40))
            cmd.Parameters("@StartDate").Value = DateTime_StartDate.Value
            cmd.Parameters.Add(New SqlParameter("@EndDate", SqlDbType.DateTime, 40))
            cmd.Parameters("@EndDate").Value = DateTime_EndDate.Value
            cmd.Parameters.Add(New SqlParameter("@Location", SqlDbType.Text, 100))
            cmd.Parameters("@Location").Value = txt_Location.Text.Replace("'", "''")
            cmd.Parameters.Add(New SqlParameter("@LookUp_FinancialYearIDAuto", SqlDbType.Int))
            cmd.Parameters("@LookUp_FinancialYearIDAuto").Value = ComboBox_FinancialYear.SelectedIndex()
            cmd.Parameters.Add(New SqlParameter("@BranchID", SqlDbType.Int))
            cmd.Parameters("@BranchID").Value = g_UserCentre
            cmd.Parameters.Add(New SqlParameter("@ProgrammesIDAuto", SqlDbType.Int))
            cmd.Parameters("@ProgrammesIDAuto").Value = m_ProgrammesIDAuto

            cmd.ExecuteNonQuery()

            If m_ProgrammesIDAuto = 0 Then
                MessageBox.Show("New Programme Successfully Saved!", "Save Successful", MessageBoxButtons.OK, MessageBoxIcon.Information)
            Else
                MessageBox.Show("Programme Successfully Updated!", "Save Successful", MessageBoxButtons.OK, MessageBoxIcon.Information)
            End If

            GroupBox_Details.Enabled = False
            GroupBox_ProgrammeData.Enabled = False
            txtSearch.Focus()

        Catch ex As Exception
            MessageBox.Show(Err.Description)
        Finally
            cnn.Close()
        End Try

    End Sub

*********************************

CREATE PROCEDURE procInsertProgrammes
      @UserCreated varchar(35),
      @DateCreated datetime,
      @JobClubNumber varchar(100),
      @JobClubNumberSeries int,
      @StartDate datetime,
      @EndDate datetime,
      @Location varchar(100),
      @LookUp_FinancialYearIDAuto int,
      @BranchID int,
      @ProgrammesIDAuto int

AS
      If @ProgrammesIDAuto = 0
      BEGIN
            Insert into Programmes (UserCreated,  DateCreated, JobClubNumber, JobClubNumberSeries, StartDate, EndDate, Location, LookUp_FinancialYearIDAuto,BranchID)
            Values (@UserCreated, @DateCreated,  @JobClubNumber, @JobClubNumberSeries, @StartDate, @EndDate, @Location, @LookUp_FinancialYearIDAuto, @BranchID)
      END
      Else
            Update Programmes
            Set UserCreated = @UserCreated,  JobClubNumber = @JobClubNumber, JobClubNumberSeries = @JobClubNumberSeries, StartDate = @StartDate,
            EndDate = @EndDate, Location = @Location, LookUp_FinancialYearIDAuto = @LookUp_FinancialYearIDAuto, BranchID = @BranchID
            where ProgrammesIDAuto = @ProgrammesIDAuto
GO