Push notifications not working on 3.5 inch iPhones

Hello , 

I am an iOS developer and i am using WindowsAzureMessaging library 

I was working on my iPhone 5 and Push notifications was working well 

Until i discovered my app on iPhone 4s doesn't receive the push notifications 

I had two bad experiences using the azure messaging library :

1-Once the problem was that it's working good on iOS 7.0 and has bugs not sending on iOS 6.2 properly 

2- I downloaded a buggy sdk that refused to work until support answered me that there's an update and once downloading the update it worked good 

So I want to make sure if the problem is not a Microsoft side this time because every time it takes a lot of time and i discover that the problem is not from my side at the end 

Thanks in advance 

Yours , 

John Maher