Radio back-lights turns off??? what gives?

[AsGs300]

Hi, My sister has a 99 Rx 300 great car, I myself have a GS300, recently it started acting up, when she turns on the headkights the backscreen on the radio goes away, which also controls the A/C i belive however i do hear a clicking noise under the dash whenever i turn on/off the lights
anyone have this problem? if so how can i fix it ?

Thanks in advance

[Lexmex]

Has she tried pushing the right side of the brightness control with the headlights on?

[AsGs300]

yup, its not that it just clicks off