I guess you didn't know but jagex updated the stringing process. I ran your script and I saw it was still going by the old stringing process of clicking string then bow, over and over.
The new update made it so you just have to click the string and bow once then click make all. But your script would work perfectly if it was still using the old way. If you can somehow fix it to work with the new update it will be great.
Hope I helped.
I found the hacker...
But he pwnd my icon...
That makes me a sad panda.