I tried sending my daughter a picture and for 2 days it said pending and was never sent. What's with that? When I had a NON Smart phone, I sent pictures easier than I have with this so called smart phone.
Do you have an active cellular data connection (4G or 3G symbol) when you try to send the attachment?
Try sending a picture message to yourself and see if it goes through.
You cannot send MMS (picture) messages with ONLY the WiFi enabled. You must also have DATA enabled simultaneously with WiFi when you are using WiFi.
OTOH, you can send MMS messages with ONLY Data enabled (no WiFi).
JerryF