Czech defence ministry deems it against its interests
Vera is a passive surveillance system; unlike ordinary radars it does not emit any signals, but only listens for, collects and processes signals from other radars, aircraft, ships or terrestrial vehicles. Most importantly, it can detect American stealth aircraft.
But the Pakistani army cannot have it. The Czech decision must have pleased both Amnesty International (which campaigned against the sale) and the US Defense Department (which flies those stealth aircraft).