Hello
Every time I execute my python-script in the end it says 
| Runtime error  Traceback (most recent call last):   File "<string>", line 52, in <module>   File "c:\program files (x86)\arcgis\desktop10.3\arcpy\arcpy\management.py", line 7211, in SelectLayerByAttribute raise e ExecuteError: ERROR 000229: Cannot open Rest\Kartenausschnitte A3 mit Aussparung Legende. 1:2500 und 1:3000 Failed to execute (SelectLayerByAttribute). |  | 
So this is the "bad" part of my script. lyrkartenausschn is "Rest\Kartenausschnitte A3 mit Aussparung Legende. 1:2500 und 1:3000"  |  | 
 cursor = arcpy.da.SearchCursor(lyrkartenausschn, [seitenzkartenausschn])     seitenliste = int(19)     del seitenliste     seitenliste = []     for row in cursor:         seitenliste.append(int(row[0]))     print seitenliste      for seite in seitenliste:         for elm in arcpy.mapping.ListLayoutElements(mxd, "TEXT_ELEMENT"):             if elm.name == seitex:                 elm.text = str(seite)                 pfdausgabePDFeinzeln = pfadausgpdf[0:-4] +"_"+ str(seite) + ".pdf" #Path         arcpy.SelectLayerByAttribute_management (lyrkartenausschn, "NEW_SELECTION", seitenzkartenausschn + " = " +  str(seite))         mxd.dataDrivenPages.exportToPDF(pfdausgabePDFeinzeln, "SELECTED") #PDF Export         mxd.dataDrivenPages.printPages(druckername, "SELECTED") #  Print     mxdspeicher = ausgpdfmxd + "\\" + bewirtschafter + ".mxd"     mxd.saveACopy(mxdspeicher)     del row     del cursor     del seite     del seitenliste     del elm     arcpy.RefreshActiveView()  |  | 
There's a lot of things I'm doing bevore. So if I leave the "bad" part, it loops trough the whole script perfectly. If I add this part, the error appears.
I also tryed to add the line "arcpy.SelectLayerByAttribute_management (lyrkartenausschn, "CLEAR_SELECTION")" at the verry bottom, but then the same error appears for this line.
So what's wrong with the code? do I have to del something more? or "deactivate" data driven pages? (maybe it's a problem because it's still printing? but then how can I make it wait until it's finished?
thank you for your help!