Not sure what all you tried. I usually do okay with casinos, but have been having more issues lately with that red box of death. Things that I try before I give up: First make sure I have gone to the correct webpage--every once in awhile I have the wrong casino site. Next, uncheck the check mark, go the casino webpage, refresh it and put the check mark back in. Wait a few seconds--sometimes it will fix itself if I just wait. Uncheck the box, go back to the start of the task and repeat the whole thing from the beginning and place the check mark in the box again while saying a little prayer.
Today I had two that did not want to go the first time and while doing the above they did go eventually. But yesterday I had one that no matter what I did it just would not go. It is a recognized issue at CrowdFlower, but seems to be something that happens in a small percentage of cases so probably is very tough to trace the issue.