Can I use Old YPN Invitation?

I had got YPN invitation long back, but did not bother to make any of use it, today I replied to the invitation mail,asking whether I can use it now.
but got an automated response asking me to contact customer support. Can someone send me the url/email address where I can ask this question, Can I get a new invitation if the old invitation is not valid?

 

i think u cant. invite will be expired if u dont use it for a long time.

 

Actually you can. I applied with an email I never used, I thought I applied with my primary email. Anyway, I was accepted but the invitation had inspired 2 months ago. I still registered though and it worked fine.