Help with plugging waste pipe?

[Tomhurst]

Firstly I'm not a plumber so apologies in advanced.

I've got a waste pipe that goes through some cupboards in my kitchen. There's a hot water pipe above it, so I guess it's for a dishwasher or something, but we haven't got anything connected to it.
There's never been anything plugged in, but it's started leaking water if the washing machine is on or if the sink is draining. Think it's not draining quickly enough.

Anyway, I bought a mcalpine 1.5" T23U blanking end. Basically it's only got a screw on one side but not the other. I can either screw it onto the pipe, but then can't screw the blanking end into it. Or I can screw the blanking end into it, but then I can't screw it into the pipe.

Does that make sense?
Basically it would be perfect if the screw bit was double sided. Does anyone know what I can buy? Thanks

 

[Howsie]

McAlpine T23U Multifit Blanking Plug White 40mm | Compression Waste | NoLinkingToThis

 

[Tomhurst]

If you can see, this side doesn't have a screw bit

 

[Tjdservices]

If you can see, this side doesn't have a screw bit
View attachment 25851

Post a phot of the current set up if you can

 

[Tomhurst]

Post a phot of the current set up if you can

The bit that the water is actually coming out of I unscrewed, so I can screw different ends onto it. But here is the pipe

 

[Howsie]

Why not take that whole fitting off and use the blank end posted eairler?