Piwik visits are x3 lower than GA and Quantcast visits (no replies)

Hi Everyone!

We have site http://www.24hacrepair.com/ (WordPress).

When I see the visits data on piwik analytics its x3 Lower compare to the quantcast visit data.

We have GPSS (Google Page Speed Service) also Varnish Cache on the site.

We have lastest version of the piwik and I do not understand what is the problem?

Any suggestions will be appreciated!

Thanks in Advance!