Thread: Problems using multiple plugins with ClassiPress 3.4 and WP4.1

Problems using multiple plugins with ClassiPress 3.4 and WP4.1

Trying to find some help please.

I've already tried everything but I still get problems using multiple plugins with ClassiPress 3.4 and WP4.1.

If I activate one of these plugins separately all is well:
- Contact Form 7
- All In One SEO by Yoast
- All In One WP Security

When I activate a second plugin I get a white screen and sometimes HTTP error 500.

To solve it, or to see where the problem is, I removed the ClassiPress theme.
Then I have activated the theme Twenty Thirteen.

Now I can activate all plugins simultaneously without problems.

Then I installed a fresh copy of the ClassiPress again and when I switched the theme to ClassiPress. Again a white screen.

Am I doing something wrong or what?