proxy question

hi, i just recently figured out how to use a proxy in firefox.. i was going to use this to create a few yahoo accounts under the radar only problem is no matter which proxy i use from my list they wont get me past the captcha on signup.. it shows up but every time i type the right thing it says please try this one instead. any helpp would be greatly appreciated been stuck for few hours

I believe Yahoo blocks certain known proxy IP ranges.
I even had this with private proxies from my former supplier.

My current private proxies work fine with Yahoo.

try using socks proxie
instead of http proxie
sometimes works

i been on the socks proxys for like the last 3 -4 hours lmao, i appreciate all the help! i just cant seem to figure this one out.. anyone know if craigslist is the same way?

Thank you