Localization Server, Join Group sends me to the White Screen of Death

This is the same basic problem as #1827374 Can't Join Group. See comment #14 on that issue for necessary dependencies and permissions. That issue and it passed tests, and I'm getting a different result now, so I'm opening a new issue.

I've set up a localization server and on the home page clicked on "Add content". I selected "Translation group" to create a new translation. I use Spanish. This gives me a page ?q=translate/languages/es for the overview.

I created a new user "test", logged in as test, and went to the Spanish project. Down in the lower, right-hand corner is a link "Join." When I click on it, I get a blank screen. I've since learned that the Drupal community calls this the white screen of the death (WSOD). I've worked through some of the suggestions this page, but without any success.

When I'm logged in as administer, I can edit the test user and give him a Group Membership of Spanish. This makes him a member of the Spanish group and I no longer fight the Join button. But that defeats the purpose of the Join button.

I have a hunch that this is a permissions issue, but I haven't yet been able to figure out what they might be. Maybe I'm just being slow.

Modules:

• core: 7.19
• l10n_server: 7.x-1.x-dev (dated 2013-Feb-20)
• og: 7.x-2.0
• Entity API: 7.x-1.0
• chaos tool suite: 7.x-1.2
• Plural formula configurator: 7.x-1.2