OAB Exchange 2013 error

Hi Team, i have issue with OAB outlook download. error bellow

i have two mailbox Role,two CAS Role, and one OAB. My OAB arbitration mailbox only maounted at MBX2. when i check lzx file at MBX2, lzx is update. but when i checked at MBX1. the lzx file is missing. only bin and web config. when the outlook error downloading OAB, user mailbox database is mounted at MBX1 ( where the lzx is missing ).

is there a normal condition? 

what exactly the issue of that error? :)

thanks

Regards