I have a custom object which has a Master-Detail relation to Opportunity. (i.e. Opportunity is Master and Custom Object is Detail).

When I created the Custom Object I had set this relation as a simple lookup relation. So I had an Opportunity lookup on my Custom Object. I could then add the custom object tab to my customer portal. (i.e. by making it visible on the Customer Portal profile that I have created).

When I change the relation to a Master-Detail relation as mentioned above The Custom Object tab is automatically switched off on my Customer Portal Profile. When I check the Customer Portal Settings for the selected tabs list I have the tab for the Custom Object in my selected tabs list.

When I then try to switch on the Custom Object tab on my Customer Portal Profile I get the following error:

"Error: Invalid Data

Review all error messages below to correct your data.
Permission Read Evaluation Licences depends on permission(s): Read Opportunities"

How do i change the permission on the Opportunities to Read? Am I missing something here?

Any advice is appreciated.

Ballal