Why a DUA Doesn't get ANSWERED?

True Islam Quran and Sunnah with No Shirk and Bidah" 
Why a DUA Doesn't get ANSWERED?
"Sometimes our duas are NOT Answered. Some of those reasons eventually become obvious to us with the passage of time and some don’t. 
However, as Muslims we should understand the reasons to help us better cope with situations when our Duas are Not being answered.
This can help us influence factors that are under our direct control.
We know from Quran and Hadith the many reasons behind Duas Not being accepted. Some of them are the following:
The Dua that a person is asking may not be good for the person but that person may not know the reasons yet;
A person’s sins may be in the way of accepting Duas;
A person earns his living through unlawful means (haraam means);
A person may be asking for forbidden or sinful items;
In the Quran, Allah says:
“And it may be that you dislike a thing which is good for you” [Surah Al-Baqarah, 2:216]