Keyless entry problem diagnosis/fix

[András]

Here is one thing I figured out; if the key is in my bag, next to my mobile phone, the keyless entry fails sometimes. Especially on the trunk close button. I do not know the exact reason, but the phone interferes with the key's signal. 

If that is not the problem, I have an other idea. Do your keys have motion detection? Maybe try shaking it around a little while trying to open the car and see if that changes anything.