Ikea sink to waste problem

[benjamin88]

Hey guys! I'm no DIY'er but have managed to replace our kitchen sink with a bigger one from ikea. I've done everything I can and now have the main grey ikea pipe into the pipe that leaves the property. The problem is that the connection between the grey ikea pipe and white...connector part leaks slightly and drips (please see attached). Can anyone advise on how to go about connecting it properly? I've just literally placed the pipe into the white connection, it doesn't seem to connect securely because of the ridges on the pipe. I've attached an image of the setup. Any advice is appreciated. Thank you.

 

[snowhead]

You are missing a part, it's probably on the waste on the old sink.
It's the compression nut like there is on the bottom of the white waste connector.
There should be a rubber taper washer with it.