Make sure the trailer is plugged into "shore power"...... If it still isn't working, it's possible maybe your 7 pin connector is not wired to the "standard" line-up? http://cdn.airforums.com/forums/atta...4&d=1366933754
A little troubleshooting with a meter should verify this. I'd start with the connector at the rear of your vehicle first, turn the key to the on position & verify you have 12 volts coming through each pin when each "function" is being used. Ex. you should always have 12 volts coming through the green (clearance/running light) pin. When you turn on the left signal you should get a 12 volt
reading on & off through the red pin etc...