I have a problem with piwik conversion tracking which has been bugging me for quite some time now and after countless research I am running out of ideas where the problem might lie.
The thing is: On our site we use Google Analytics and Piwik for conversion tracking. While both platforms succeed in tracking conversions we usually track 20% less conversions with piwik than with GA.
First I thought the problem might be that the ecommerce-tracking requests sent to piwik are sometimes incomplete (i.e. lack data). However I can rule this out now as I have constructed a side script which logs all request data before it is sent to piwik.
I also do not necessarily think that it has anything to do with https as both our piwik installation and our shop have a SSL-certificate. However when we just started to experiment with piwik we had some problems there as we first did not have a SSL-certificate for piwik. This has been obviously changed now but it might be that we have still an old version of the tracking script hidden in the depths of our sever which still might try to send data to piwik (but to the old “http domain” and not the new “https domain”). Do you think that the problem might be there?
Otherwise I do not really have any other clue.
Therefore I please ask for your help. Do you have any idea what might cause the tracking difference of 20% between Google Analytics and Piwik?
I am grateful for any advice! Thanks!