Twists that are don't last long

My twists do good most of the time. But lately,  they have been falling  out about 2 weeks AFTER I get them done. I keep my hair clean and put a scarf over them at night. But my hair has a problem  keeping  the twists in. Especially  my edges area. They seem tight (not to the point of pain and agony). Do I need to change the texture of the Marley hair I buy? 

2 Answers

Can you share a photo of your hair?
I couldn't  get a picture of my real hair for it is in twists  currently. But this is EXACTLY  what my real hair looks like on this girl. It may be a little  longer because I'm 2 years post relaxer. Woohoo! Go naturals! The second  picture  is actually  me after 2 weeks of twists. The front and edge twists  fell out.