cannot iMessage from iPhone to iPad?

I have my ipad updated and set it to use my email for the imessage in my iPad
then, I realized that I cannot type "@" in the imessage in iPhone (therefore, cannot type mail address)
how to do send an imessage from iPhone to iPad?
in the message app in iPad, you can type "@", but you cannot do that in the iPhone version of the iMessage?
WTF is that?

yeah, that is the workaround I am doing right now, but is there anyway to do that in the iMessage app?

on an iPhone (only iPhone, not iPad) with iOS5,
go to home screen, and tap "Messages"
tap the icon upper right corner that will let you write a new message,
in the "to" field, where you normally put in a phone number,
you CANNOT type a "@" in that field with the soft keyboard, because there is no "@" button. You can, however, copy and paste the "@" tho.

Then, in the preference, if you enable MMS, and come back the the "Message" app. only then, you will find a "@" button in the soft keyboard.

That is all, I finally figure it out, thanks!