Lead Source does not Appear as a Link on a Custom Role

On a Customer record > Marketing tab, the value of the Lead source field is not showing as a link. If this happens, the role does not have a permission for Marketing Campaigns. To resolve the problem:

1. Navigate to Setup > Users/Roles > Manage roles > Customize/Edit role.

2. On the Permissions tab > Lists subtab > make sure that Marketing Campaign permission is on the list.

3. Click Save.