Why am I able to select a sender and type a message, but not send it?

[iMore Question]

i can select a sender and type a message but not send it

 

[Just_Me_D]

Does the recipient have an iOS device capable of receiving "iMessages"? If the recipient does not or the device you are texting is not an Apple device, you will not be able to send because iPads cannot send "SMS" messages.