If her idea was "when you pay me x, you get 3x back in new revenue" and your idea was a tarpit idea like "help people find what to eat tonight", it's really obvious why you failed.
if you done the same and have 0 customers that means you did something incorrectly.
it is IMPOSSIBLE to do the same thing that works and net 0 customers.
In reality the agents are not identical (e.g. different skillsets, or attractiveness to clients), and the environments are different (e.g. different professional or social networks).
And, as another commenter pointed out, the time when agents are starting is also a factor, but my point is that even if they start at the same time the result might be different.
Lastly, there is a butterfly effect - that small changes in the initial conditions may result in vastly different outcomes.
My partner started a business and literally from her first ad she was inundated with customers. Now it's a $10m/year bootstrapped business. I've done exactly the same thing and had 0 customers.
If you are falling into the Hard Fact / Future Vision categories it can very hard to get customers because no one is ever looking for your product.