Several weeks ago, I hosed bugs, dirt and spider webs out of my exterior porch light but the light has not worked since then.

I've already taken the porch light down and:

• replaced the socket inside the fixture
• replaced the wiring inside the fixture
• replaced the bulb
• replaced the wall switch

but the light still doesn't light.

I've confirmed that the socket, internal wiring, switch and bulb are good so I suspect the problem is with the wiring between the switch and the fixture -- inside the stucco wall. (The fixture is only about 3 feet from the switch).

How can I determine where the problem is and how can I fix it?