Golf 5 1.9 tdi reverse light - Reverse light. No communication.

Hello all. I need help.
On my Golf 5 I have a problem with the reverse light. It is not a golf Variant. I only have the right one and the other fog. Min problem is that in the west it shines to me that the reversing light is defective, but the light works. When I delete it with a copy, of course, the error disappears, but when I throw it in reverse, it lights up again. Sometimes it is so that when I get in the car and go somewhere without including the reverse, it is ok. But then the error returns again. I try to turn it on with a write-off, but there is no communication with him. But the light works normally. I replaced the Bordnetz but it didn't help. Normal bulb 12v .. I don't know what's going on. Give me some ideas. Best regards.

start by replacing the bulb.

it often happens that wearing it causes similar problems.

Ok. But why I can't turn it on with a write-off and when I hit the reverse, it shines normally.