Knit Pro needles?

So ......... since the lovely little wool shop 'Babes in the Wool' had sold out of 100cm circular needles, I thought I'd give the Knit Pro needles a go..... because those she had, in the size I wanted.

I've not used them before and yes they are nice to use but ....... am I doing something wrong folks?
I screwed them in position and set off garter-ing away and after 2 rows found the yarn snagging on the screwed in areas.
So I re-tightened the end points and set off again ............ but every 2nd or 3rd row the yarn is catching as the end appears to unscrew!

I feel inclined to glue the blessed ends into the wire centre!!
Which of course defeats the object of having the multi size Knit Pro system.
I must be doing something wrong............right?
Have you used them and had this happen too?
Or is it, more likely, my cack-handed knitting style? lol

We have snow again ........... not like the deluge many of you have had thankfully and  it's already raining, so by morning I imagine we'll have some icy road conditions.
I hope your snow is melting back at last!

Anyway, I opened the back door earlier on, to let Max out for a constitutional and found these little footsteps right outside the door ............... hope he/she found something to eat whilst on ground level!