Checking if text boxes are empty - vb.net

Question

I have a winform with a bound datagridview, 4 text boxes and a button. With the click of the button the "fillby" statement is called, the data is loaded on the datagridview and the content of the text boxes become the default value of some fields in the new rows of the datagridview.
I need to check all the text boxes to make sure they're not empty, if any of them is empty then a message should pop up saying which text box is empty and also keeps the datagridview from filling.
This is the code I have so far:
Private Sub btnCargarInformacion_Click(sender As System.Object, e As System.EventArgs) Handles btnCargar.Click
Dim emptyTextBoxes =
From txt In Me.Controls.OfType(Of TextBox)()
Where txt.Text.Length = 0
Select txt.Name
If emptyTextBoxes.Count >= -1 Then
MessageBox.Show(String.Format("Please fill following textboxes: {0}", String.Join(",", emptyTextBoxes)))
Else
Dim PartePersonalTableApt As New PersonalObraDataSetTableAdapters.PartePersonalTableAdapter
Dim PersonalObTableApt As New PersonalObraDataSetTableAdapters.PersonalObTableAdapter
PartePersonalTableApt.ClearBeforeFill = True
PartePersonalTableApt.FillByFecha(PersonalObraDataSet.PartePersonal, txtDate.Text, txtDepartamento.Text, txtTurno.Text)
PersonalObTableApt.ClearBeforeFill = True
PersonalObTableApt.Fillby(PersonalObraDataSet.PersonalOb)
End If
End Sub
I don't get any errors, the message appears even if all textboxes are filled, the message box does not specifying any text boxes as empty and stops the datagridview from filling.
I'm very new to codding so please explain in more detail your solution. Thanks

Answer 1

.Count >= -1
The count will be 0 if it's empty
If emptyTextBoxes.Count <> 0 Then
MessageBox.Show(String.Format("Please fill following textboxes: {0}", String.Join(",", emptyTextBoxes)))
Else
Dim PartePersonalTableApt As New PersonalObraDataSetTableAdapters.PartePersonalTableAdapter
Dim PersonalObTableApt As New PersonalObraDataSetTableAdapters.PersonalObTableAdapter
PartePersonalTableApt.ClearBeforeFill = True
PartePersonalTableApt.FillByFecha(PersonalObraDataSet.PartePersonal, txtDate.Text, txtDepartamento.Text, txtTurno.Text)
PersonalObTableApt.ClearBeforeFill = True
PersonalObTableApt.Fillby(PersonalObraDataSet.PersonalOb)
End If

Answer 2

You can try to loop at your container (ie form, panel, groupbox) for each textbox without content, then increment whenever there is a textbox that doesn't have content.
Example:
Dim checkr as integer = 0
Dim this As Control
For Each this In that.Controls
If TypeOf this Is TextBox Then
If this.text = "" then
Checkr += 1
End if
End If
Next
If checkr > 0 then
msgbox("Cannot proceed because a textbox has no content")
Else
'......(what you were gonna do)
End If