For some reason I can't iMessage from my iPad. I can receive messages, but when I type to reply, the send button stays faded (not lit up/I can't press it). That problem happens both on 3G and with wifi. Also, my iPod touch is hit or miss with iMessage when on wifi. I'm wondering, does the recipient need to be on wifi for me to send them a message? Can I not iMessage people when I'm only on 3G on the iPad? And can I not iMessage iPhones or iPads unless they are on wifi and not only on 3G? Thanks.