Users of old nokia devices without touch, can´t receive my texts from my iphone 5c, ios 8.3

I´ve already tried to switch the imessage ability off, but it háven´t helped anything. I send a message to a user of an Nokia old device without touch (with Buttons) and on my display it shows me that it has been sent, but my friend can´t receive the message. Huge Problem -> quick help pls.