Reporting Service security

I have a Reporting Service report which sits in a remote server. I need to display the report in a ReportViewer control in a dotnetnuke portal. The report was displayed fine when I test in a stand alone web page, but when I deploy the user control in the DNN portal, I got the following security message:

The permissions granted to user 'BIOLAB\AD_ALANZ$' are insufficient for performing this operation. (rsAccessDenied)

It turns out the account used in my local computer doesn't have enough permission to view the report.

I did a search through web and solved by the following steps:
Go to the report manager home page. Click on Properties tab.
Click on New Role Assignment button.
Add a new user BIOLAB\AD_ALANZ$, choose Browser role from the list and click Apply.

Then my report is showing in the ReportViewer successfully.