Freelander 2 (LR2) Roof rails

Hi.
I bought a Freelander 2 with a panoramic sunroof.
I am trying to get a set of roof rails for this vehicle, does anybody know why the rails for a non sunroof LR2 are not suitable to use on my vehicle.
If any body has a set of rails I would be interested in buying them.

Many thanks

It's because of the crossbar clearance to allow the sunroof to open

Many thanks Freelance. Our local Land Rover dealer, Guy Salmon, did not know that.
I guess its the expensive option for me then, over £100 difference for a higher cross bar.
Thanks once again for your help.