Could be lots of things. Could be your hair doesn't like the protein in your leave in. Could be you need more moisture to balance it. Could be that protein in a daily leave in is too much for your hair.
For me (fine hair) PTs are very important, but I don't have protein in all my products. It doesn't make much difference to me if I have daily protein or not. JaJC has fine hair too. She can't do PTs at all, but must have protein in her daily products.
http://pedaheh.blogspot.com/ (a blog to help new wavies, go to the how do I get started page)
2a (nc.com) 2bFi (Fia), very fine, thin, low/normal elasticity, porous, CG, doesn't get weighed down
Cowash: Tresemme naturals
Rinse out/leave in: Renpure Organics (red)
Curl enhancer: FSG
Gel: BRHG, Salon care aloe, Ecostyler Krystal (normal dews)
PT: ION effective care, IAgirl's gelatin PT
Low Poo: renpure (red), Ion swimmers