How to use an external USB keyboard with a Galaxy S II or a Huawei Y201 Pro The background:

I recently learned about OTG USB cables that can be used to connect peripherals to Android devices. I had this idea of using an android device with a usb barcode reader connected (which basically acts like a keyboard) and an in-house developed app, for stock management in a warehouse.

The first step was to buy the OTG cable. The second was to start testing peripherals connected our existing Android devices.

The problem:

When I connect any USB device to a Huawei Y201 Pro (4.0), there is no feedback from the device. No error, no response from the input, nothing.

When I connect mouse to a Galaxy S II, it recognizes the usb cable, then a cursor appears on screen and all works great. However, when I connect a keyboard (I tried around 5 so far), a notification says that the cable was connected but right after that it says that no devices are connected.

My question:

Is there something I'm missing to make this work?

If not, some secondary follow up questions: What are the things I should look for in making this idea work? Is this connectivity more dependent on the Android device? OS version? Peripheral?
Maybe your mobile doesn't support OTG. It may also need to be connected via a powered USB hub in order to provide enough power.