Power issue

I have a Sony VLP-HW40ES in my theater, controlled along with the rest of the equipment by the Simple Control app on my iPad. Infrared is handled by an iTach ethernet-to-IR device. The one function I cannot control is the powering up and down of the projector, everything else works great. I’ve tried teaching the IR command to the IR repeater but the Sony just doesn’t respond. I can see the LED blink to indicate transmission. Since all the AV equipment is in another room, I have few wired options. But there is a spare 4-conductor unshielded cable I can use. Actually, I tried using that with a mini plug wired to the IR out on my Yamaha receiver, with no success.
Is there anything any of you smart people can suggest?

Have you exhausted all the IR debugging? Playing around with delays and repeat counts often fixes problematic IR. Did you do the teaching with the actual iTach learning mode utility or the Roomie learning mode command? (iTach has a standalone PC-based learn utility.)

Will a hard power control at the A/C plug work? You could get a WiFi controlled A/C power switch like Belkin WeMo or iHome SmartPlug.
They come with an iOS app to turn the attached device on or off. You could “launch” the app from Roomie using a url command, or if you are more capable, most of these devices have a REST API that you could configure more directly with different URL’s for “Device on” and “device off”.