My Cell Won't Send a Text Message to Just One Person in Contact List?

I have Verizon Wireless and my phone is the Palm Pre 2. I can send and receive text messages usually, but for some reason this one certain number it won't send to. And I know this person receives text messages from other peoples phones too. I've tried deleting the number from contacts and re-entering it in, tried just typing the number rather than choose the person through my contact list, I've tried everything it seems. If I go to the contact in the contact list and try to click on the little "SMS" square for that number, it won't let me. If go to text messaging, type the number or go from contact name, type a message, hit send, it just doesn't register at all even on my screen or outgoing messages or anything. Is this just a glitch in my phone or am I missing something lol Please help cause of all people number it's not registering is my boyfriends number who lives 5 hours away lol