Request value consists of the descriptor type as the high byte and the index of the interface as the low byte. Descriptor type in our case is HID Report or 0x22 (this is from the HID spec, specifically class descriptors). Index of the interface is the same as request index below. In my case it was 0x00, but yours may be different. Combining the high and low bit, we get 0x2200 for our request value.