1987 Questions for all other cars indicators

Electrical problem
1987 Questions for all other cars Engine Size unknown Wheel Drive Type unknown Manual 30000 miles

hi
when you turn the indicators on the left side of my holden astra 87 it works ok until you apply the brakes then the globe just stays lit and dosnt flash. It works ok when you dont brake and the right side works fine to can you tell me possible problems I have tried a new globe it dint make a difference