Can I just ask if the leaves you speak of are new ones, just opening, or whether the tree has leaves left on since last year?

last year

leaves left on from last year

Master of the concise answer, I see, Raydar, lol! Okay, if you're saying they're all on there, and none have dropped, but they look dead, not sure why that would be unless the leaves died back really, really early and the tree itself is dead. Result of drought? You don't say how old the tree is, or rather, how long its been planted. If you're saying there's just a few still 'stuck' to the tree, try pulling them off, if you can reach, but in that case, I wouldn't worry about it - as long as new growth arrives with spring, they'll disappear eventually.

Not so unusual as you might think, some of the varieties do retain their leaves long into the winter. I have the cultivar 'Gum Ball', still more or less in full leaf, albeit very tatty looking right now.

i have thee trees one 2 years one 4 years & one7 years they don't colour in autumn as they should but keep most ther leaves till late winter

They don't all have crimson or red leaves in autumn, Raydar - depends on the variety. Liquidamber 'worplesdon' for instance has leaves which just turn a sort of yellowy colour. One of the best varieties for red leaves in autumn is 'Lane Roberts'. And clearly, retention of the leaves appears not to be uncommon, given Bluespruce's experience.