super cache does not detect desktop or tablet

Hi

I am using WP Supercache on http://www.magoster.nl. In the homepage php detects desktop, tablet or phone and there-after builds specific content.

With empty cache the tablets gets the homepage for tablet. But after showing the homepage on dekstop the tablet gets the homepage for desktop. When showing the homepage on dekstop a phone gets the right one, namely the homepage for phone.

So it seems that desktop ánd tablet gets the page from cache. I have now excluded the homepage from caching but is there a better solution?

A css-solution does not work in this case. It is php that builds tables that fit within the screensize.

Regards
Rudolph Smits
Netherlands