La Prealpina Roof Bars Locking Mechanism - Not Locking

[Mosaic]

I've managed a really annoying start to the weekend by installing the prealpina roofbars on my Mazda 3. Strangely translated but reasonable instructions, bars fit OK. Come to the last bit, which is a locking plastic cover that clicks over each 'foot' and contains a small barrel lock.
The barrel lock will not fully insert and engage.
It will when the component is not attached to the roofbars but when in the correct place they seem to be blocked by the metal of the foot.
Any suggestions?
Am I doing it wrong?
Is there a trick I've missed?
Is it too early for gin?

[Toureman]

Why not ask in the correct catogary?

http://www.theanswerbank.co.uk/Motoring/

[Mosaic]

is there an award for 'least helpful answer?'

[Mamyalynne]

Hmmmmmmmmmmm

[Mamyalynne]

Is there a helpline with the roof bars ? I know these can be a pain but worth a try.

[Mosaic]

Thanks Mamy - I believe I found one of the few remaining companies who close for the whole weekend....had a word this morning so replacement keys should be on way.