avondale rear lights

last week i went to cornwall and just before leaving found my n/s caravan indicator not working. after changing bulbs xtill didn't work so to a chance and went away. on returning i thought it might be the caravan plug. i changed the plug and wired it the same as the original one. now another problem has arisen when the rear lights are on and i put on the o/s indicator all the lights flash except the indicator and the n/s indicator still isn't working. have double checked the plug wiring which is ok. have been in touch with a caravan engineer who would want £94 to fix. which seems alot any ideas?