I'm not sure where you're seeing AC1129. This is what is available, according to ExpertFlyer:
Results from https://www.ExpertFlyer.com
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Flight Availability Search
Departing YYZ on 06/21/19 12:00 AM for YXE
Flying AC
Direct/Non-Stop Only
Frequency
Flight Stops Depart Arrive Aircraft Reliability Available Classes
0 Connections
AC 1121 0 YYZ YXE E90 F,Sa J3 C3 D3 Z3 P3 R2 Y9 B9 M9 U9 H8 Q5 V4 W3 G2 S0 T0 L0 A0 K0
06/21/19 7:50 AM 06/21/19 9:19 AM 69% / 13m
0 Connections
AC (**) 1541 0 YYZ YXE 321 Daily Y8 B6 M4 U3 H2 Q0 V0 W0 G0 S0 T0 L0 A0 K0
06/21/19 12:55 PM 06/21/19 2:25 PM NA / NA
0 Connections
AC (**) 7539 0 YYZ YXE E75 Daily J4 C4 D3 Z3 P3 R2 Y9 B8 M6 U4 H3 Q1 V0 W0 G0 S0 T0 L0 A0 K0
06/21/19 11:10 PM 06/22/19 12:42 AM NA / NA