That's odd - You do have to send the 'keyup' event as well, so:
Might do it?
However, in the 'HID Report' you have to give a 'logical maximum', which is the maximum keycode value you intend to send. In http://www.espruino.com/modules/ble_hid_keyboard.js you can see
0x25, 0x73, // Logical Maximum (115 - include F13, etc) and again a few lines later
So if the above doesn't work, you could try copying the hid_keyboard code into your project, and changing
0x25, 0x73, to
0x25, 0x93, (as well as the line below)