Fingerprint, Double Tap to Wake dont work in Standby?

Hello everybody,

i have a problem with fingerprint and double tap to wake.
i get the problem with stock rom and custom rom (eragon 1.5 now).

i lock my P9000 via button on the right side.
directly after that i can unlock my phone via fingerprint and i can wake up via double tap.

after about 5 mins the fingerprint sensor no longer responds if i put my finger on it.
double tap to wake works only at second or third time.

so i have to unlock my phone via button and pincode -> lock via button on right side -> now i can use fingerprint and double tap to wake.
after 5 min same problem.

does anybody have the same problem? is there a special deep sleep mode or something like that?

Thanks in advance!
(sorry for bad english) :D

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