The sensor for the IR shutter signal on the 70D is that dot on the front of the grip, below the shutter button (see page 20 of the user manual).

You must point the remote at that dot, so these types of IR remotes rarely work well from behind the camera, but work much better from in front of the camera.

In addition, it's much like a television remote, since it works on IR. If you are outdoors in bright sunlight, the signal can easily be overpowered, and without bounce surfaces around for the "master" signal to get to the sensor, reliability and range can become compromised. This type of triggering system works best when used indoors in studio-like conditions.

You may also want to check the health of the battery in your remote (just like a TV remote, a weak battery will put out a weaker signal).

If you are going to be using a shutter remote outdoors in sunny weather a large amount of the time, you may want to look into getting a radio triggering system instead--many low-cost manual flash triggers can do double duty as both flash triggers and shutter remotes. They come with two units: one you use as a transmitter and the other as a receiver. You take the receiver and hook it up to the cable release port, and then you use the transmitter as your in-hand remote.