To view the denial reason for your claim, you first will need to click the Account link in the navigation, post login. On the next page you will need to click the "Click Here" link within the sentence "Click Here to view claim history."
After clicking the "Click Here" link, the next page you are directed to will provide you with a list of your submitted claims. Locate the claim in question. Click the "View" link next to the claim ID. The next page will provide you with a Comments section which will provide you the reason why your claim was denied.