50.000 Stepps ~ 500 Coins earn by Walk ?Not realy??

i Walk over 50.000 Stepps.. 

now i Exchange my points for a Google Play Card But.. 

i  cant redeem this.. the App Show me the error Message i musst Walk 50.000 Stepps (earn 500coins with Walk) bevor i can Exchange the coin for cards!! I dont know.. 

you know??