Option Explicit
Private Sub CommandButton1_Click()
If Trim$(txtVorname.Text) = "" _
Or Trim$(txtNachname.Text) = "" Then
Call MsgBox("Bitte füllen Sie die Felder für Vor-/Nachname aus.")
Exit Sub
End If
Dim wks As Excel.Worksheet
Dim strName As String
strName = txtVorname.Text & " " & txtNachname.Text
If WorksheetExists(strName, ThisWorkbook) Then
Call MsgBox("Ein Arbeitsblatt mit dem Namen '" & strName & "' existiert bereits.", _
vbExclamation)
Else
Set wks = ThisWorkbook.Worksheets.Add
wks.Name = strName
End If
Set wks = Nothing
End Sub
Private Function WorksheetExists(WorksheetName As String, Workbook As Excel.Workbook) As Boolean
On Error Resume Next
WorksheetExists = Not Workbook.Worksheets(WorksheetName) Is Nothing
End Function