Theres something you need to learn about this site and the artists. When none of us reply it means one of several things:
1.) They did not see the thread.
2.) They do not frequent this forum.
3.) They frequent the forum and saw the thread but are not interested.
So when no one replies, its safe to assume any of the above three (with the third being the most likely one a majority of the time). You're not being ignored, so bumping and double posting is not necessary. No response IS a response and it usually means no or not right now. Rest assured if people were interested they would post and let you know what they think.
I will suggest to you what I suggest to everyone else- Choose an artist you would like to draw it and then PM them and request it. You're at least guranteed to get a response that way, but expecting one here is not necessary. Some artists might also have their own request or suggestion threads, so those can be utilized aswell.