First of all, thank you for you fast response. Since i'm still in the process of developping the website, it isn't online yet. And as a result, I can't provide you with an URL. Is there any other way I can provide you with the code?
In the meantime I've tried a few things to narrow down the options a bit. I disabled all the plugins (one by one) but this had no influence on WPDiscuz displayed. However when I switched themes from Salient (the theme I use) to one of the standard wordpress themes like twenty fiftheen I saw that reply and edit button showed up correct this time. However the vote-up, vote-down and the number of votes still didn't show up like they should..
Thanks in advance