Hallo Olli,

teste mal:

Private Sub CheckBox1_Click()

With Worksheets("Tabelle1") 'Blattname anpassen
    Me.TextBox4 = ""
        'Daten aus Spalte L in Textbox
        If Me.CheckBox1 And Not Me.CheckBox2 And Me.ComboBox1.ListIndex > -1 Then
            Me.TextBox1 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:L"), 12, False), "0.00")
            'Daten aus Spalte O in Textbox
            Me.TextBox2 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:O"), 15, False), "0.00")
            Me.TextBox3 = ""
        ElseIf Me.CheckBox2 And Not Me.CheckBox1 And Me.ComboBox1.ListIndex > -1 Then
            'Daten aus Spalte M in Textbox1
            Me.TextBox1 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:M"), 13, False), "0.00")
            'Daten aus Spalte K in Textbox2
            Me.TextBox2 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:K"), 11, False), "0.00")
            'Daten aus Spalte P in Textbox3
            Me.TextBox3 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:P"), 16, False), "0.00")
        ElseIf Me.CheckBox1 And Me.CheckBox2 And Me.ComboBox1.ListIndex > -1 Then
            'Daten aus Spalte N in Textbox1
            Me.TextBox1 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:N"), 14, False), "0.00")
            'Daten aus Spalte O in Textbox2
            Me.TextBox2 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:O"), 15, False), "0.00")
            'Daten aus Spalte R in Textbox3
            Me.TextBox3 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:R"), 18, False), "0.00")
        Else
            Me.TextBox1 = ""
            Me.TextBox2 = ""
            Me.TextBox3 = ""
            Me.TextBox4 = ""
        End If
End With
    
End Sub

Private Sub CheckBox2_Click()

With Worksheets("Tabelle1") 'Blattname anpassen
    Me.TextBox4 = ""
    If Me.CheckBox2 And Not Me.CheckBox1 And Me.ComboBox1.ListIndex > -1 Then
        'Daten aus Spalte M in Textbox1
        Me.TextBox1 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:M"), 13, False), "0.00")
        'Daten aus Spalte K in Textbox2
        Me.TextBox2 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:K"), 11, False), "0.00")
        'Daten aus Spalte P in Textbox3
        Me.TextBox3 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:P"), 16, False), "0.00")
    ElseIf Me.CheckBox1 And Not Me.CheckBox2 And Me.ComboBox1.ListIndex > -1 Then
        Me.TextBox1 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:L"), 12, False), "0.00")
        'Daten aus Spalte O in Textbox
        Me.TextBox2 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:O"), 15, False), "0.00")
        Me.TextBox3 = ""
    ElseIf Me.CheckBox2 And Me.CheckBox1 And Me.ComboBox1.ListIndex > -1 Then
        'Daten aus Spalte N in Textbox1
        Me.TextBox1 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:N"), 14, False), "0.00")
        'Daten aus Spalte O in Textbox2
        Me.TextBox2 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:O"), 15, False), "0.00")
        'Daten aus Spalte R in Textbox3
        Me.TextBox3 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:R"), 18, False), "0.00")
    Else
        Me.TextBox1 = ""
        Me.TextBox2 = ""
        Me.TextBox3 = ""
        Me.TextBox4 = ""
    End If
End With

End Sub

Private Sub ComboBox1_Change()

With Worksheets("Tabelle1") 'Blattname anpassen
    If Me.ComboBox1 = "" Then
        Me.TextBox1 = ""
        Me.TextBox2 = ""
        Me.TextBox3 = ""
        Me.TextBox4 = ""
        Exit Sub
    End If
    Me.TextBox4 = ""
    If Me.CheckBox1 And Not Me.CheckBox2 Then
        'Daten aus Spalte L in Textbox1
        Me.TextBox1 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:L"), 12, False), "0.00")
        'Daten aus Spalte O in Textbox2
        Me.TextBox2 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:O"), 15, False), "0.00")
        Me.TextBox3 = ""
    ElseIf Me.CheckBox2 And Not Me.CheckBox1 Then
        'Daten aus Spalte M in Textbox1
        Me.TextBox1 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:M"), 13, False), "0.00")
        'Daten aus Spalte K in Textbox2
        Me.TextBox2 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:K"), 11, False), "0.00")
        'Daten aus Spalte P in Textbox3
        Me.TextBox3 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:P"), 16, False), "0.00")
    ElseIf Me.CheckBox1 And Me.CheckBox2 Then
        'Daten aus Spalte N in Textbox1
        Me.TextBox1 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:N"), 14, False), "0.00")
        'Daten aus Spalte O in Textbox2
        Me.TextBox2 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:O"), 15, False), "0.00")
        'Daten aus Spalte R in Textbox3
        Me.TextBox3 = Format(WorksheetFunction.VLookup(Me.ComboBox1, .Range("A:R"), 18, False), "0.00")
    End If
End With

End Sub

Private Sub CommandButton1_Click()

If Not Me.CheckBox1 And Not Me.CheckBox2 Then
    MsgBox "Es wurde keine Auswahl getroffen."
    Exit Sub
End If
If Me.CheckBox1 And Not Me.CheckBox2 And Me.ComboBox1.ListIndex > -1 Then
    Me.TextBox4 = Format(CDbl(Me.TextBox2), "0.00")
'End If
ElseIf Me.CheckBox1 And Me.CheckBox2 And Me.ComboBox1.ListIndex > -1 Then
    Me.TextBox4 = Format(CDbl(Me.TextBox2) + CDbl(Me.TextBox3), "0.00")
'End If
ElseIf Me.CheckBox2 And Not CheckBox1 And Me.ComboBox1.ListIndex > -1 Then
    Me.TextBox4 = Format(CDbl(Me.TextBox2) + CDbl(Me.TextBox3), "0.00")
Else
    MsgBox "Bitte ein Schiff auswählen."
End If

End Sub

Der Code gehört komplett ins Codemodul deiner Userform. Die Namen deiner Textboxen/Checkboxen/Combobox und des Tabellenblattes mußt du ggf. noch an deine Verhältnisse anpassen.

Gruß Werner