PLT OF SMA SEL OVERSHOT ASSIGNED ALT DUE TO INST AND INST PANEL LIGHTS PROB DISTR.

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CLBING OUT OF KEY WEST AT DUSK I WAS UNABLE TO GET PANEL LIGHTS TO WORK PROPERLY. WHILE TRYING TO GET PANEL LIGHTS ON I NOTICED SUCTION WARNING LIGHT WAS ON; BUT SUCTION INST WAS READING IN THE GREEN (NORMAL OPERATING RANGE). WHILE TRYING TO DECIDE WHICH INST TO BELIEVE; I CLBED THROUGH ASSIGNED ALT OF 4000 FT. LESSON LEARNED IS NOT TO FIXATE ON ANY PROB; BUT CONTINUE TO MONITOR ACFT INSTS. CORRECTIVE ACTION WAS TO RETURN BACK TO 4000 FT. ALSO; DURING THIS FLT I WAS ABLE TO USE SOME OF THE PANEL LIGHTS; WHICH WAS WHY I CONTINUED THE FLT AFTER LNDG AT NAPLES TO CHK WX. HOWEVER; AFTER TAKING OFF FROM NAPLES I ENTERED RAIN SHOWERS AND CLOUDS WHICH MADE THE COCKPIT EVEN DARKER. I TOOK OUT MY FLASHLIGHT TO BE ABLE TO READ THE CHARTS; BUT IT ONLY WORKED 30 SECONDS TO 1 MIN BEFORE THE BULB WENT OUT. THAT MADE IT NEXT TO IMPOSSIBLE TO READ THE CHARTS; SO I ASKED ATC FOR DIRECTIONS TO THE NEAREST ARPT; WHICH WAS PAGE FIELD IN FORT MYERS. I ELECTED TO LAND AT FORT MYERS AND SPENT THE NIGHT. I RETURNED TO DAYTONA BEACH VFR THE NEXT MORNING.