You included the x within the path string. Since it is a variable you need to place it outside like:
"G:\PEP\04.Kaizen\KAIZEN Audit\02 Auditfragebögen\5S questionaire\" & x)
Also make sure that you enter the full file name (so with extention) when prompted by the inputbox for the code you created.
Monday, Tuesday and Thursday are usually the days I'll respond. Bear this in mind when awaiting a reply.