percent+number thing is called “percent-coding” and is a method to encode symbols for the URL, so 28 is
( and 29 is
) (see here as well).
You didn’t provide any code samples but I assume that that’s the problem, considering what little information you provided. If it doesn’t work please edit your question. Also, next time you should google a bit before you ask, and when you do ask always include the relevant code sample.