Check your settings. Make sure your default e-mail is one that can send from wherever you are. For example, I have a POP account that I can only use to send mail if I am at home. So, now, my default e-mail (the one the iPad uses when sending from an app such as Safari) is an IMAP account (Gmail, in my case).
To change your default e-mail: Go to your Settings app, then select Mail, Contacts, Calendars. Then, on the right side, scroll down until you see the line Default Account. Pressing on it will allow you to choose whichever account you wish...
That's all I can think of as a solution. If that's not it, please holler back and we'll take another stab at it. Good luck.
Marilyn