Homebrew PCBs

Hi All

Please help. I purchased a piece of pre treated photo resistant pcb.
I removed the black protective layer and exposed my positive onto the board
by placing it in direct sunlight.
After 1 hr, I removed the positive and had a perfect image of my pcb design
on the pcb.
This is when it starts to go wrong.
I then placed the board in pre-made / purchased etching solution / ferro
chloride.
After much time, nothing has been etched.
What am I doing wrong?
Have I missed out something?



Stuart