ERROR: SoomlaStore failure: IabActivity is destroyed during purchase.

I am using unity soomla, for In app Billing. Hi, I have a problem Just IN SOME DEVICES, After that I purchase, or even cancel the purchase when activity return to unity, the app will Unfortunately has stopped. And after that when I start the game again, successful purchase will call and for example the diamonds will given. What is the problem? I am using unity 4.6.8 soomla core 1.0.2 and store 1.7.7

I am using this thread https://cafebazaar.ir/developers/docs/iab/platforms/?l=en for purchasing with Bazaar. and here it is the log file for error:

 11-12 12:34:41.417: E/SOOMLA SoomlaStore(24943): ERROR: SoomlaStore failure: IabActivity is destroyed during purchase.
 11-12 12:34:41.627: E/AndroidRuntime(24943):     at com.soomla.store.billing.bazaar.BazaarIabService$OnIabPurchaseFinishedListener.onIabPurchaseFinished(BazaarIabService.java:380)
 11-12 12:34:41.627: E/AndroidRuntime(24943):     at com.soomla.store.billing.IabHelper$5.run(IabHelper.java:357)
 

if you need more logs file please tell me.