Error while connecting to SSRS

You need to add the user in report manager and set what permissions he should have:
Permissions:
http://msdn.microsoft.com/en-us/library/aa337491.aspx

From Msdn:
Permission to access report server content and operations are granted through role assignments. On a new installation, only local administrators have access to a report server. To grant access to other users, a local administrator must create a role assignment that specifies a domain user or group account, one or more roles that define the tasks the user can perform, and a scope (usually the Home folder or root node of the report server folder hierarchy). You can use Report Manager to create the role assignments.
http://msdn.microsoft.com/en-us/library/aa337279.aspx

But this user have all permission on that machine. It is domain admin user..
What could be problem?

Thanks a lot ..
That issue is not there but now we are facing some other isssue

Logon failed. (rsLogonFailed)
For more information about this error navigate to the report server on the local server machine, or enable remote errors

but credentials are ok.

Did you add the domain user like the picture below shows?
ssrs.png

Now that issue is also resolved.

but getting other issue. please find attached image
error1.JPG

That seems to be a IIS problem with the web site INSIMPADMIN, check the iis if the web app is ok.

Good that the access problem is solved then.

Please look at https://www.experts-exchange.com/questions/24378489/Report-viewer-control-is-not-working-in-Windows-2008.html this issue as well