A320 brakes question

[Chiquitete]

319 IAE,62t.Push back finished,both engine starts normal,clear signal received,release brakes and...the thing does not move.Ok,maybe some thrust because we have an uphill...the thing does not move.N1 40% on both engines and nothing.Aircraft shaking because of the thrust and it does not move a single inch.Everything normal on brakes and hyd systems,no ECAM at all.Engineers can not help because never seen this before.After shutting down engines next attempt the plane starts to taxi without touching thrust levers.
Any of you has seen this before?why does it happen?
Any info much appreciated.

[tubby linton]

Did you look at the indications on the triple gauge?The parking brake selector is merely an electrical switch and it had been known to fail.

[Chiquitete]

Sure,gage indications normal,either with brakes set or released.

[AKAAB]

I've had a parking brake valve fail with similar results.