LABEL_FORMAT=P not working for the API to sheet for graphing

I tried, based on the documentation in http://help.creator.zoho.com/Creating-charts-using-Zoho-Sheet-API.html, to create labels on the PIE chart, but no variation of upper or lower case on it works. The format should be what?

Here's the URL I was generating (replace the $ in front of 0A with a percent sign, as it gets stripped out in this editor):

http://sheet.zoho.com/zohochart.do?&title=Excludes Not answered&charttype=PIE&LABEL_FORMAT=P&width=600&height=300&chartdata=Complexity,Count$0ALarge,1$0AModerate,5$0ASmall,5