isn't there any way that you can know who is down-voting or up-voting your posts ? if yes, then how can i know that ? thanks ;)
No, there is no way by which a Daniweb member can know who is down/up voting his/her posts.
may be this feature can be added. ;)
Not happening unfortunately. In a distant past, the only way to show appreciation/disdain towards a post was "add reputation" feature which publicly showed the name of the person adding/deducting your reputation. As you can imagine, it resulted in up/down rep flame wars between individuals and groups. In short, it was quite a mess. Plus some folks are not comfortable with their name being showed when they like/dislike a post and prefer to remain anonymous. The public nature of the system drastically reduced the voting/rep activity on the site.
The current system is an attempt to get around those peculiar situations. If you want to publicly express your like/dislike, just use the add/remove reputation feature. If you wish to remain anonymous, use the up/down voting feature. Of course we are open to complaints wherein a given member is continuously down-voted on all his posts by a single member or is a target of an auto down-voting script.
Looking at your reputation score in your profile, I can see that there have been 8 different members who have upvoted your posts and 8 who have downvoted. That said, I really wouldn't worry so much about who is downvoting posts, but instead I would look at the posts which have been downvoted and consider why that might be the case. If you learn from your mistakes and adjust how you react to situations then I imagine the downvoting might stop and you could even start getting more upvotes.