Implementations count.
Implement your idea. Preferably, implement it and show the value of it.
Then pitch it.
I've had random stuff I've thrown together in a few minutes turn out to be highly valuable. One was a script I'd assembled for some datagathering on my own systems. Ended up showing it to the customer support team where I was working, got thanked a couple of years later by one of the team-members who'd remained post-acquisition who said that it had pretty much saved the asses of everyone there by making it trivially easy to gather forensic data from users' systems. Just as one example.
Other tools I'd created and shared which turned out to be useful in other contexts, with similar stories.
But don't feel too badly at having a good idea shot down. This happens to many clever people. Unfortunately, politics rule decisions in many companies. And as a new guy in this type of situation, you may have to build up some credibility before people will take you more seriously and possibly stick their neck out for you.
People who are skeptical of anything not accompanied by evidence are called ... scientists. If you want to adapt, become a scientist yourself -- don't put your ideas forth without any evidence to support them.