Sometimes there are extra seconds on the bar because the selected video/gif isn't as long as 11.17 seconds. It may very well be in the "null zone" making you unable to actually generate the gif.
How do I deal with this error? The start and end times are CLEARLY in the video time range. Here are the times I'm using, and I'll put a link to the video I'm using in comments to see if anyone else has the same problem.