The likelihood of finding a planet with ALL the requirements to support life AND for that life to exist at all, much less to be intelligent enough to build a transmitter, are virtually nil. The odds are like 1:10e-300.
The problem is when. Some scientists have posited that the amount of time a civilization with a comparable lifespan to ours has between developing radio and collapse from war/pollution/disease is 100-200 years.
Collapse from war/ pollution/disease AND the alien equivalent of Democrats will make that window shrink to near zero! ;)
Was that the global warming scientists or the nucular winter scientists?
Some scientists have posited that ...
Bogus science both
I'll throw in a couple of other factors: If a species becomes technologically proficient as to develop radio as a medium of communication, it may be that the same species either develops some other means (leveraging quantum entanglement?) within 200 years, or perhaps recognizes that it might not be such a good idea to broadcast your existence out to a universe which is fundamentally hostile and/or hungry, and so they employ less leaky modes of communications (direct line of site lasers?)