Описание ошибки преобразование из строки "firstnametextbox.text" типа' ' В тип integer недопустимо для поиска по сетке

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Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSearch.Click

        On Error GoTo SearchErr
        If txtsearch.Text = " " Then
            Call notfound()
            Exit Sub

        Else
            Dim cantfind As String = txtsearch.Text
            Me.dgvfill()

            DoctorBindingSource.Filter = ("Doctor_s_NHS_NoTextBox.Text  like  '" & txtsearch.Text & "'")("FirstnameTextBox.Text like '" & txtsearch.Text & "'") & _
               ("SurnameTextBox.Text like '" & txtsearch.Text & "'")("Medical_Center_NameTextBox.Text like '" & txtsearch.Text & "'") & _
                ("Email_AddressTextBox.Text like '" & txtsearch.Text & "'")("Patient_NHS_NumberTextBox.Text like '" & txtsearch.Text & "'") & _
                ("GP_Appointment_RefTextBox.Text like '" & txtsearch.Text & "'")("Patient_IDTextBox.Text like '" & txtsearch.Text & "'")

            If DoctorBindingSource.Count <> 0 Then
                With DoctorDataGridView
                    .DataSource = DoctorBindingSource
                End With
            Else
                Me.notfound()
                MsgBox("--> " & cantfind & vbNewLine & _
                       "The search item was not found", _
                       MsgBoxStyle.Information, "Hey Boss")
                DoctorBindingSource.Filter = Nothing

                With DoctorDataGridView
                    .ClearSelection()
                    .ReadOnly = True
                    .MultiSelect = False
                    .DataSource = DoctorBindingSource
                End With

            End If

        End If

ErrExit:
        Exit Sub
SearchErr:
        MsgBox("error number" & Err.Number & vbNewLine & _
               "error description " & Err.Description, MsgBoxStyle.Critical, _
               "reset error!")
        Resume ErrExit

    End Sub

    Private Sub reset()
        Dim txtS As TextBox = txtsearch
        With txtS
            .Text = ""
            .Select()
            .BackColor = Color.LightCyan
        End With
        cboOfColor.SelectedItem = "MistyRose"
        cboAltColor.SelectedItem = "Gold"

        cboOfColor.BackColor = Color.LightCyan
        cboAltColor.BackColor = Color.LightCyan
        If DoctorDataGridView.DataSource Is Nothing Then
            Exit Sub
        End If
        Dim dgv As DataGridView = DoctorDataGridView
        With dgv
            .RowsDefaultCellStyle.BackColor = Color.FromName(cboOfColor.SelectedItem)
            .AlternatingRowsDefaultCellStyle.BackColor = Color.FromName(cboAltColor.SelectedItem)
        End With

    End Sub
    Private Sub dgvfill()
        txtsearch.BackColor = Color.LightBlue
        If DoctorDataGridView.DataSource Is Nothing Then
            Exit Sub
        End If
        Dim dgv1 As DataGridView = DoctorDataGridView
        With dgv1
            .RowsDefaultCellStyle.BackColor = Color.FromName(cboOfColor.SelectedItem)
            .AlternatingRowsDefaultCellStyle.BackColor = Color.FromName(cboAltColor.SelectedItem)
        End With

    End Sub
    Private Sub notfound()
        Dim txtS As TextBox = txtsearch
        With txtS
            .BackColor = Color.White
            .Select()
            .SelectAll()

        End With
        If DoctorDataGridView.DataSource Is Nothing Then
            Exit Sub
        End If
        Dim dgv2 As DataGridView = DoctorDataGridView
        With dgv2
            .RowsDefaultCellStyle.BackColor = Color.White
            .AlternatingRowsDefaultCellStyle.BackColor = Color.White
        End With



    End Sub

End Class

Что я уже пробовал:

я пытаюсь инициализировать эти поля как целое число, но все равно возникает ошибка ...потому что я думаю, что в начале текстового поля есть"", которое делает его строкой...пожалуйста, помогите мне

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