I have a website running on App Engine and I store my data in Datastore. If the text contains Turkish letters, they are replaced with ? in a diamond. But interestingly, sometimes I edit them and they appear fine or while they appear correct they start to contain <?> again.
I don't know when it happens and when it doesn't. So I change something in the code, then it works, but later I see those <?> again. I call it mysterious because of that and I don't know how to explain better. I will try again if it's not clear.

It is 2013 and I am struggling with characters :/ By the way, I am not expert on web development, I am learning while making this. So maybe I forgot a very simple thing.
Please create a record here to see (I can delete them later or you can delete afterwards)

http://petkayit.appspot.com/app

These are the turkish characters for copy pasting: ş ı ğ
Thanks