Ok, the valve has 3 "ports". One from the pressure side of the turbo pipework (call this 'in'), one return to the turbo intake (dump), and one line to the inlet manifold (sense).
Under normal driving conditions, both sense and in are at the same pressure, and the spring acts to keep the valve closed. When you close the throttle, there is still positive pressure at the 'in' port, but now the sense line is pulling a vacuum, this difference across the valve overpowers the spring, causes it to open, and the pressure waiting at the 'in' port is released thru the 'dump' port. The spring is now acting so that when the pressure drops the valve will close again.
Given that in closed throttle, after-dump situations there is often much more vacuum in the inlet than is present at the DV's 'in' port, the spring needs to be strong enough to keep the valve closed even though there is a difference across the valve. It also needs to be strong enough to keep the valve shut under big boost (even though both sides of the valve should be at boost pressure, and therefore the forces on the diaphram equal, in practice you need a heavier spring to stop it leaking)
What this means is if you only have say 2 or 3 PSI at the 'in' port, the spring is often strong enough that the valve wont open, and you'll get a bit of compressor stall. Its more likely to happen with the 710N as it has a stronger spring then the 710/710A valve. Compressor stall at 2-3psi really isnt a problem, so if thats all thats happening then i wouldnt worry about it.
If however your getting stall when coming off the throttle at full boost, then i suggest that theres something odd going on! Possibly a blocked vacuum hose or a faulty dump valve.