Outside fluorescent light

bad sensor.

New electronic two wire sensor made for incandescent load used to replaced old three wire thermal switch (or relay) sensor that worked with any load. Add a 40w incandescent to the fluorescents or find sensor not marked "for incandescent(or resistive) load only".

-- larry /dallas

The solid state switch is shot.

Have you tried with a replacement incandescent bulb? Many electronic controls can not control a ballasted light without a resistive load also on the circuit. (X10 products are a good example)

Re-read the post, used wrong bulbs, or ballast is bad (dried out caps). there are at least three types of bulbs these days. Pre-heat lamps- used "starters". Rapid Start lamps- no starters. The new eco lamps that are lower wattage and work with the new eco or electronic ballasts- lower power factor, usually rated 32w for what would have been a 40w, smaller diameter- T8 instead of T12. There was another bulb design but I don't remember it's name or characteristics. Check Don Klipstein's pages.

-- larry/dallas

you need a relay-based sensor for flourescent, a resistive sensor is only for incandescent.

Some sensors pass small amounts of current through the bulb so the sensor has power.

I am guessing your bulbs don't like that. Have you tried a regular bulb?