FLT FOLLOWING DENIED TO NIGHT VFR ACFT.

Narrative

I DEPARTED X20 ABOUT PM30 LCL AND CLBED TO 7500 FT VFR TO SUA. I CONTACTED FSS AND WAS GIVEN THE FREQ FOR FLT. FOLLOWING; I RECEIVED MY SQUAWK CODE AND PROCEEDED ON COURSE. AS I APCHED THE MIAMI VOR; I NOTICED THE CLOUD LAYER BECOMING OVCST AND RISING SLIGHTLY. NOT WANTING TO BE TRAPPED ON TOP; I STARTED CIRCLING OVER A HOLE AND CALLED APCH FOR LOWER. AFTER MANY ATTEMPTS; I WAS GIVEN A NEW SQUAWK CODE AND TOLD TO DSND (I WAS NOT CLRED INTO THE CLASS B AIRSPACE). AT 5500 FT; I BELIEVED THE CLOUD LAYER WAS STILL BLOCKING MY PATH SO I REQUESTED; MANY TIMES; A LOWER ALT. FINALLY; IN A HURRIED VOICE; I WAS GIVEN 'FLT FOLLOWING NO LONGER AVAILABLE SQUAWK VFR' OR SOMETHING SIMILAR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR IS AN INSTRUCTOR FOR A FLT SCHOOL IN FLORIDA; HE WAS ABLE TO TURN AROUND AND CONTINUE TO HIS HOME BASE VFR. HE WAS UPSET WITH THE TREATMENT GIVEN HIM BY MIA TRACON. HE NOW BELIEVES THAT HE WAS NOT INSIDE THE CLASS 'B' AIRSPACE; JUST ON THE EDGE OF IT. AS THIS WAS AT NIGHT; HE WAS UNABLE TO DETERMINE HOW CLOSE HE WAS TO THE CLOUDS.