Remapped Commands only work in some windows

Remapped Commands only work in some windows

I have a new keyboard that has a split spacebar, backspace on left thumb,
space on right thumb. Before getting this keyboard, I was using the short
cut Ctrl+Alt+Space to open Launchy. With this new keyboard, I would ALSO
like to be able to use Ctrl+Alt+Backspace.
I added the following mapping to AutoHotKey
^!BS::
MsgBox Working
SendInput ^!{Space}
return
If I have certain windows open (say Notpad), pressing Ctrl+Alt+Backspace
shows the message box, and then launches the program as expected (the
Launchy binding to Ctrl+Alt+Space is controlled by it's own options UI
stuff). However, certain windows (e.g. Powershell) seem to swallow the
SendInput part, so I will see the message box, but Launchy will not open.
What can I do to get AutoHotKey to send it's commands into the regular
message queue instead of to the active window.
Note: I have already tried using various different combinations, but it
doesn't seem to work.