Porque no funciona esos calculos

Private Sub CommandButton1_Click()
Dim chevo As Long

Dim Fecha As Date
Dim Fecha1 As Date
Dim Time1 As Date
Dim Time2 As Date

Time1 = DTPicker3
Time2 = DTPicker4
TextBox6 = Time1
TextBox8 = Time2
Sheets("Arbeitstelle").Range("G2") = Time1
Sheets("Arbeitstelle").Range("I2") = Time2

Fecha = DTPicker1
Fecha1 = DTPicker2
TextBox7 = Fecha
TextBox5 = Fecha1
Sheets("Arbeitstelle").Range("H2") = Fecha
Sheets("Arbeitstelle").Range("F2") = Fecha1

If Me.TextBox1.Value = "" _
Or Me.TextBox2.Value = "" _
Or Me.TextBox3.Value = "" _
Or Me.ComboBox1.Value = "" Then
Call MsgBox("The fields are not complete", vbInformation, "Edit Contact")
Exit Sub
End If
Son_Dolu_Satir = Sheets("Arbeitstelle").Range("A65536").End(xlUp).Row
Bos_Satir = Son_Dolu_Satir + 1
Sheets("Arbeitstelle").Range("A" & chevo.Value = _
Application.WorksheetFunction.Max(Sheets("Arbeitstelle").Range("A:A")) + 1
Sheets("Arbeitstelle").Range("B" & chevo.Value = TextBox1.Text
Sheets("Arbeitstelle").Range("C" & chevo.Value = TextBox2.Text
Sheets("Arbeitstelle").Range("D" & chevo.Value = TextBox3.Text
Sheets("Arbeitstelle").Range("E" & chevo.Value = ComboBox1.Value
Sheets("Arbeitstelle").Range("L" & chevo.Value = ComboBox2.Value
Sheets("Arbeitstelle").Range("F" & chevo.Value = TextBox5
Sheets("Arbeitstelle").Range("G" & chevo.Value = TextBox6
Sheets("Arbeitstelle").Range("H" & chevo.Value = TextBox7
Sheets("Arbeitstelle").Range("I" & chevo.Value = TextBox8
Sheets("Arbeitstelle").Range("J" & chevo.Value = TextBox9.Text
Sheets("Arbeitstelle").Range("M" & chevo.Value = TextBox10.Text
Sheets("Arbeitstelle").Range("N" & chevo.Value = TextBox11.Text
Sheets("Arbeitstelle").Range("M" & chevo.Value = TextBox12.Text
Sheets("Arbeitstelle").Range("L" & chevo.Value = Val(ComboBox2) * 25 / 100
Sheets("Arbeitstelle").Range("O" & chevo.Value = TextBox14.Text
Sheets("Arbeitstelle").Range("J" & chevo.Value = Val(TextBox8) - Val(TextBox6) - Val(TextBox12)
TextBox10 = Val(textebox5) + Val(textebox8) - (Val(textebox7) - Val(textebox6))
Sheets("Arbeitstelle").Range("O" & chevo.Value = ((Val(TextBox9) + ComboBox2.Value)) * Val(TextBox9)
TextBox6 = Format(TextBox6, "hh.mm")
TextBox8 = Format(TextBox8, "hh.mm")
Sheets("Arbeitstelle").Range("M" & chevo.HorizontalAlignment = xlRight
Sheets("Arbeitstelle").Select
ListBox1.Clear
refresh
Label14.Caption = ListBox1.ListCount
End Sub