Pool Light doesn't work.

[originate]

Lights on my pool weren't working - found that GFCI wouldn't reset. Replaced the GFCI and the old twitches for good measure. Spa light now works great, as does a socket in the backyard. But, when I turn on the switch to the main pool light, the GFCI trips.

When I pulled the main light out, and disassembled - a sucking sound occurred (indicated an air seal was still in tact?)
The inside of the light was moist, but no standing water.
I noticed some corrosion, I sprayed in some electrical connector cleaner from a home store, and then some club soda and scrubbed with a toothbrush. The recepticle looks a lot cleaner, but no improvement - still trips the GFCI - even without the light bulb in.
At the junction box, I disconnected all the wires - with a volt meter I couldn't detect any short between the lines.
I re-connected the white and black lines and the light turned on without issue.
With the switch off, I connected the green lines - GFCI tripped again.

Is that green line important?

At the recommendation of my pool guy, I'm having the light fixture sit out overnight and see if it drys out.

[PoolDoc]

With the switch off, I connected the green lines - GFCI tripped again.

Is that green line important?

I'm pretty strict about the sort of help we give on electrical questions, because electricity and pools mix FATALLY. And at the risk of offending you, I'm going to simply say, your question "Is that green line important?" tells me beyond all doubt you should NOT be working on this yourself.

Hire an electrician, or at the least a buddy who understands "that green line", or else turn the breaker to that light OFF . . . before you kill someone in your family.

Sorry . . . .