The problem is because you probably just use a space " " character for a hotkey. Instead, you need to use the keyname which would be "Space" (no quotes).
You can fix this by opening up your layout configuration file which is located in
C:\Program Files\StackAndTile\Layouts
There should be a .ini file in there. Open it up, scroll to the bottom where you will find the hotkey lines. You want to look for something like:
Although yours might be hotkey2key, hotkey3key, etc depending on how many hotkeys you had set up. If there is a blank after the = sign, that is the one that you tried to use for space. Instead of having a space, actually type in the word "Space" with no quotes, then save the file, then try to start SaT.
You can fix this by opening up your layout configuration file which is located in
C:\Program Files\StackAndTile\Layouts
There should be a .ini file in there. Open it up, scroll to the bottom where you will find the hotkey lines. You want to look for something like:
Code:
hotkey1key=