Diagnosis
The iSmartGate is getting the signal and clicking the relay, but it's not sending the right 'pulse' to actually run your motor. This is almost always a wiring or learning issue with the opener itself.
How to Fix It
First, check the two thin wires running from the iSmartGate to your garage door opener's terminals. They should be screwed down tight on terminals labeled '1' and '2' or sometimes 'P1' and 'P2' on the iSmartGate side. On the opener side, they need to be on the two screw terminals where your wall button connects (often white and white/red wires). Next, you need to 'teach' your opener. Find the 'learn' button on your opener motor unit (usually a colored button near the antenna). Press it, then within 30 seconds, tap the 'open/close' button in your iSmartGate app. You should see the opener's light blink, confirming it learned the new signal.
If That Didn't Work
The issue might be the wall button itself. Temporarily disconnect the two wires from your physical wall button at the opener. Now try the app again. If the door works, your wall button is stuck in a 'held down' state, which locks out the iSmartGate signal.
Heads Up
Some older openers need a physical 'door sensor' to be connected to the iSmartGate Pro for it to operate. If your opener has safety sensors (the beam across the door bottom), the iSmartGate should have come with a small white accessory module to wire those in. Check the quick-start guide for that part.