[Rejected bugs]

I spent several hours exploring the system and found an amazing bug (at least I think so). I happily reported the bug on to Bug Tracking System and a few hours later, the bug was rejected by developers or my manager. I wonder
“I had several rejected bugs this month, I wonder if this affects my testing productivity?”
“Developers are laughing in my face for reporting an invalid bug”
“My value is going down”
“Developers don’t like me”
“I have a problem with my testing capability”

Take it easy my friend
When you test a product, you know something about the system under test, but there are also things that you don’t know yet. Testing is a learning process. When you test, you go from the known things to the unknown things.
If you have rejected bugs, it could be because you are not updated on the changed features or even don’t know if the feature exists. Learn from it and move forward.
What I’m trying to convey is that don’t let rejected bugs discourage you from finding more good bugs.