Hi, Dziem
If you're just using a single key press action for that key combo, that's probably the expected result. Whether or not the sequence of those keys matter relies completely on whether or not your target app/game accepts that input order properly.
For precision, you'll want to try breaking your key combo up into individual steps (note the pauses in between steps):
Press Shift key down
Pause .01 second
Press Ctrl key down
Pause .01 second
Press U key down
Pause .01 second
Release U key
Release Ctrl key
Release Shift key
Hope that helps!