One of my daytime running lights of my 2011 Elegance doesn't come on even though I've replaced the bulb. What could be the problem?

Probably either a broken wire or the connector for the bulb has been damaged.

 

Check you're getting 12v for both DRL and I'd also try swapping the bulb holders over from side to side.

Wiring. It's rubbish. I'm forever getting the bulb warning light and when I slip a credit card down the inner side of the unit and it pops out, the bloody bulb comes on again! Pain in the @r$e frankly.