1) Before starting
Important: Please check before connecting the lighting installations to the devices, if the installation is correctly wired and free from short circuit or ground circuit.
For that the lighting installation should be directly connected to the mains and the function of all individual lights must be checked. For 3-phase installations, the 3 phases should be tested individually (check if only the affiliated lights are responding) and then all 3 phases together. If all lights are fully ON and no fuse or circuit breaker switch falls, it can be called an error-free installation. Only after these short tests should the dimmers and control devices be connected to the installation.

2) Lamps remains dark: If all lamps remain dark in a 3-phase installation, it can be assumed that the defect is not in the dimmers.
Is the mains voltage at the entry of the dimmer(s) available ?
Check the fuse and the clamp connection !
Check the control part: is the potentiometer correctly connected ? / is the push-button control connected to the mains ?
On push-button control: is the push-button control device supplying a changing voltage ca. 1 - 10 V= at its output?
If only a single dimmer is not functioning: make a short contact on connection L and 10; if the lamps turns ON, the dimmer must be replaced, if the lamps stay OFF/dark, there is an interruption at the installation in this circuit.

3) Lamps are only full illuminated: if all lamps on a multi-phase installation are only full illuminated, it can be assumed that the defect in not on the dimmers. On a single-phase device: Test, if an incandescent lamp 60-100W is still full illuminated after disconnecting the neutral wire. If yes, then the dimmer is defective (most probably the thyristor).
Potentiometer-Control: is the potentiometer properly connected ?
Push-button Control: is it properly connected ?

4) Lamps flicker: on incandescent lamps: if all incandescent lamps on a circuit flickers permanently and can not be completely controlled up or down, these device must be replaced.
Lamps flicker at some levels only: Is the load within the correct minimum and maximum range ? At use of transformers: are electronic transformers used with leading edge dimmers, or magnetic transformers with falling edge dimmers ?? (both will destroy the dimmer !!)

5) Control range is too little: MIN and /or MAX setting of the dimmer device is probably wrong adjusted !
Depending on the control type used (potentiometer, push-button control, other device etc.) the control range of the dimmer should be adjusted to the control signal (see adjustment instructions of the dimmer).
On potentiometer control: is the potentiometer properly connected ? does it have the right OHM-value (25 K) ?