Switching Regulator (LED Driver) "Flickers"
I suspect the inductor is probably not suitable - it needs to be rated for the current (if it saturates, the inductance drops and the circuit won't work properly) and have a higher SRF than the operating frequency. You definitely need to know the specs of your inductor. Purchase one with a datasheet, and check it's suitable for use with the part.    

Another possible problem is thermal issues if you have a high current design (what is the current?) but don't have a good PCB layout as recommended in the datasheet (large solid plane underneath the IC)  

One last thing is make sure the DIM pin is not floating - tie it to Vin.