Adwords conversion tracking counts way more conversions than Piwik

Hi guys,

I am just starting out with Piwik for a client we are having the following issue.

We track conversions of a thankyou page in Adwords.

We track conversions in Piwik. Somehow the conversions in Adwords are way more than in Piwik.

I have tagged the adwords landingpages with the Piwik Url Builder to make sure everything is tagged ok.

For example: Adwords measures 35 conversions, than Piwik measures 2 conversions from google/cpc

Do you have any advice which things to check to find out why this gap is more than 30%?

Greetings tako