There is a thing called a "ballast" sort of like fluorescent lights have.
You may have installed the switch between the ballast and the light bulb? The switch would need to be before the ballast of course.
And these have a power on sequence - designed to be turned on and left on, not on/off. Might try leaving it off for about 20 minutes, then back on. They need to cool down before switching back on.
This power on sequence you can see with street lights or parking lot lights. At first they start dim, then get brighter.