How to use an URL that can display an opportunity from an email sent by a workflow

 Hi, When a customer account is updated by another user than owner, a workflow sends a warning email to the owner. In the received email text, the owner can click on the URL to display the customer account in CRMOD:

https://secure-ausomxdba.crmondemand.com/OnDemand/user/AccountDetail?OMTGT=AccountDetailForm&AccountDetailForm.Id=%%%[<AccountId>]%%%

It works for account object. I try to do the same thing for opportunity object by replacing “Account” by “Opportunity” in the URL, but it does not work:

https://secure-ausomxdba.crmondemand.com/OnDemand/user/OpportunityDetail?OMTGT=OpportunityDetailForm&OpportunityDetailForm.Id=%%%[<OpportunityId>]%%%

What is the URL that works ?