DA16200 error handling +WFJAP:0,OTHER,0

Hi, I have developed da16200mod for wifi communication.

Sometimes, DA16200mod is in unconnectable state to wifi ap.

It is responsed to '+WFJAP:0,OTHER,0'. After abnormal disconnection (mcu power reset, etc...)

It always response '+WFJAP:0,OTHER,0' about at cmd 'AT+WFJAP='ssid',4,1,'pass''.

Sometimes after a few attempts it could be connected... 

How should I handling this error? I currently handle factory reset for this error response ' +WFJAP:0,OTHER,0'.

But, It doesn't help.