I've always had difficulty getting Niagara Region frequencies that are current. Below is a list of the ones which I've found to work. These frequencies are all listed in the TAFL (freely available), maintained by Industry Canada, who issues radio frequency licenses.

The Radio Reference site has other Niagara area listings. Visit Radio Reference and navigate to their database and then to Ontario and finally Niagara. A tremendous amount of information is there.

RailCN160.415End-to-End, RTCStamford Sub, Grimsby Sub
160.365Terminal SwitchingPort Robinson Yardmaster / Oakville Ford Yardmaster
160.665Channel #4 RTCYB RTC (Halton Sub)
160.935Channel #3 RTCNI RTC (Grimsby,Stamford)
RailCP160.815Hamilton Sub RTCHamilton Sub
160.845MaintenanceHamilton Sub Maintenance
160.590Terminal SwitchingWelland Yard
161.355Terminal SwitchingWelland Yard
RailTrillium161.400Trillium Channel #1PCHR - Niagara
RailNS161.250Road WestYoungstown Line Dispatcher
161.070RoadBuffalo Line Dispatcher
161.440YardBison Yard
RailCSXT160.800RoadRochester Sub & Buffalo Terminal
160.860Road WestLakeshore Sub
161.400NF DispatcherRochester Sub
160.950NG DispatcherBuffalo Terminal
161.340NH DispatcherLakeshore Sub
160.980FrontierFrontier Yard, Buffalo
GovtPublic Works164.955C77.0City Crews/PlowsWelland
164.955C151.4"Port Colborne
169.080C151.4"Port Colborne
169.365C91.5"Fort Erie
169.440C103.5"Niagara Falls
169.560"Niagara Falls