The underlying provider failed on Open

Question

backend -> MySql

Web Admin Panel -> MVC + Entity Framwork

 

I have Two System A and B.

B is my development pc and A is server pc . my database on A(at server pc). when i work(development) in B then the db connection os working good, i can not facing any issue . but when i publish at host that on A, then the  "The underlying provider failed on Open" issue is coming. So i am not getting that why this issue is coming . 

 

i googled a lot. and try all the way which i found during searching. but i could get success to fix this issue .. so please let me suggest of anybody have idea about this .. pls