Getting Syntax Error Converting from Datetime Character String

I have the following code:

Code:

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Imports System.Data.SqlClient
Public Class Main
    Protected WithEvents DataGridView1 As DataGridView
    Dim instForm2 As New Exceptions
    Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles startpayrollButton.Click
        Dim ssql As String = "select MAX(payrolldate) AS [payrolldate], " & _
                "dateadd(s,  518399, max(payrolldate)) AS [Sunday]" & _
                  "from dbo.payroll" & _
                  " where payrollran = 'no'"
        Dim oCmd As System.Data.SqlClient.SqlCommand
        Dim oDr As System.Data.SqlClient.SqlDataReader
        oCmd = New System.Data.SqlClient.SqlCommand

        Try
            With oCmd
                .Connection = New System.Data.SqlClient.SqlConnection("Initial Catalog=mdr;Data Source=xxxxx;uid=xxxxx;password=xxxxx")
                .Connection.Open()
                .CommandType = CommandType.Text
                .CommandText = ssql
                oDr = .ExecuteReader()
            End With
            If oDr.Read Then
                payperiodstartdate = oDr.GetDateTime(1)
                payperiodenddate = payperiodstartdate.AddDays(7)
                Dim ButtonDialogResult As DialogResult
                ButtonDialogResult = MessageBox.Show("      The Next Payroll Start Date is: " & payperiodstartdate.ToString() & System.Environment.NewLine & "            Through End Date: " & payperiodenddate.ToString())
                If ButtonDialogResult = Windows.Forms.DialogResult.OK Then
                    exceptionsButton.Enabled = True
                    startpayrollButton.Enabled = False
                End If
            End If
            oDr.Close()
            oCmd.Connection.Close()
        Catch ex As Exception
            MessageBox.Show(ex.Message)
            oCmd.Connection.Close()
        End Try

    End Sub
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles exceptionsButton.Click
        Dim connection As System.Data.SqlClient.SqlConnection
        Dim adapter As System.Data.SqlClient.SqlDataAdapter = New System.Data.SqlClient.SqlDataAdapter
        Dim connectionString As String = "Initial Catalog=mdr;Data Source=xxxxx;uid=xxxxx;password=xxxxx"
        Dim ds As New DataSet
        Dim _sql As String = "SELECT [Exceptions].Employeenumber,[Exceptions].exceptiondate, [Exceptions].starttime, [exceptions].endtime, [Exceptions].code, datediff(minute, starttime, endtime)  as duration into Scratchpad3" & _
        " FROM Employees INNER JOIN Exceptions ON [Exceptions].EmployeeNumber = [Exceptions].Employeenumber" & _
        " where [Exceptions].exceptiondate between @payperiodstartdate and @payperiodenddate" & _
        " GROUP BY [Exceptions].Employeenumber, [Exceptions].Exceptiondate, [Exceptions].starttime, [exceptions].endtime," & _
        " [Exceptions].code, [Exceptions].exceptiondate"
        connection = New SqlConnection(connectionString)
        connection.Open()
        Dim _CMD As SqlCommand = New SqlCommand(_sql, connection)
        _CMD.Parameters.AddWithValue("@payperiodstartdate", payperiodstartdate)
        _CMD.Parameters.AddWithValue("@payperiodenddate", payperiodenddate)
        adapter.SelectCommand = _CMD
        Try
            adapter.Fill(ds)
            If ds Is Nothing OrElse ds.Tables.Count = 0 OrElse ds.Tables(0).Rows.Count = 0 Then
                'it's empty
                MessageBox.Show("There was no data for this time period. Press Ok to continue", "No Data")
                connection.Close()
                Exceptions.saveButton.Enabled = False
                Exceptions.Hide()
            Else
                connection.Close()
            End If

        Catch ex As Exception
            MessageBox.Show(ex.ToString)
            connection.Close()
        End Try
        Exceptions.Show()
    End Sub

    Private Sub payrollButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles payrollButton.Click
        Payrollfinal.Show()
    End Sub
End Class

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and when I try to debug this, I get this error:

System.Data.SQLClient.SQLException: Syntax error converting from datetime character string, line 57.

Which is this line:

adapter.Fill(ds)

When I debug this, I put the line break on that line and look at the Table Value, which shows 0, but I know that there is data for that time frame. Can anyone please assist?