Intalling PIWIK in ojs 3.1

Please contact ctgraham, asmecher or bozana regarding that issue.

Thanks @vvucic
Waiting from @asmecher @bozana @ctgraham

@anupent
Do you any idea how to solve this?

Sorry all, It solves now.

What resolved the problem, @kawahyu?

I think I installed older piwik
The code in line 35 https://github.com/pkp/piwik/blob/master/PiwikSettingsForm.inc.php is different. So, I tried changing the codes. It works