fail in lnk625

I am designing a flyback supply following your steps and with your elements. Bit it dpesn't work, basically thi IC lnk625 not trigger and sometime i get it trigger but not in the correctrly way. I did the test circuit for testing the work of the IC which it is suggested in in AN-45 (figure 21) and i only can see two behavourals. One of them when i get the treshold, the circuit do like a step, i mean it is in high level when i increase the bypass level up to the treshold and then go to low level............obviuosly it is a bad behavour. And the other way it is i reach the treshold and start to do something like the adjunt image and when i adjust the level of the feedback i get more or less frecuency....i am not sure about this behavour. After that when i put the IC in the complete circuit.......or not trigger or trigger from time to time but not reach the correct behavour. The desing looks good...........and all the components except the IC i am sure they work correctly...........any idea?

I want 6W and 16V