Dateien zusammenführen, Dateiname mit übernehmen

Sub DATFILESHOLEN()
Application.DisplayAlerts = False
Dim i, zaehler1, zaehler2, zaehler3, a, b, alta, altb, lzeile, lspalte
Dim lastcell As Range
With Application.FileSearch
.NewSearch
.LookIn = "G:\Files"
.SearchSubFolders = False
.Filename = "*.dat"
If .Execute() > 0 Then
For i = 1 To .FoundFiles.Count
Workbooks.Open Filename:=.FoundFiles(i)
Set lastcell = ActiveSheet.Cells.SpecialCells(xlLastCell)
alta = lastcell.Row
a = lastcell.Row
Do While Application.CountA(Rows(a)) = 0 And a <> 1
a = a - 1
Loop
alta = a
altb = lastcell.Column
b = lastcell.Column
Do While Application.CountA(Columns(b)) = 0 And b <> 1
b = b - 1
Loop
altb = b
lzeile = alta
lspalte = altb
For zaehler2 = 1 To lzeile
zaehler1 = zaehler1 + 1
For zaehler3 = 1 To lspalte
Workbooks(1).Sheets(1).Cells(zaehler1, zaehler3) = Workbooks(2).Sheets(1).Cells(zaehler2, zaehler3)
Next zaehler3
Next zaehler2
Workbooks(2).Close
Next i
End If
End With
Application.DisplayAlerts = True
End Sub