Access to path [Destination Address] is denied - Upload problem on Hosting Server (Locally works)

Hi,
I am getting dissapointed of solving the problem I have in permission granting for website folders . The problem is when I want to upload a file (through UPLOAD CONTROL) I face this error:
"Access to path [Destination Address] is denied."
The nature of my work is Visual Stuido Premium 2010 SP1, .Net 4, IIS7.
I granted read/write permission to the target folder for this user: IIS AppPool\ASP.NET v4.0 (according tohttp://learn.iis.net). So, there is no problem locally. Before that I even tried granting access to "everyone" and IIS_USERS, and it just solved the problem locally.
This error just persists on the Server and I do not have this problem in my development system. I have tried many solutions from different references but I am wondering how granting the access in local IIS might influence t ...