My first deposit/withdrawal experience with Poloniex was also frustrating and I needed to open a ticket to get it sorted out. So I understand you.
I was withdrawing 150 XLM and I believe you can withdraw less than this. Maybe something is wrong with your account. I would contact the support, they are usually fast with their response.
Also on top of this page:
https://poloniex.com/balances
you can see your daily limit. Something like "$xxxx.xx remaining of $xxxx.xx USD daily limit". It can be that you are over your limit.
Also check the profile page:
https://poloniex.com/profile
to add more verification levels if you need to withdraw a bigger amounts.
After I managed to withdraw something the first time everything else was smooth afterwards.