Network Atlas - WAN Link status not changing

Hi

In Network Atlas I dont seem to be able to make my WAN links go red after taking the WAN link down.

For example:

I've added a straight line between two routers

Within the objects Status tab I've set the line to get its status from the interfaces at either end of the WAN link.

Within Apperance I've made the colour lime green, solid, and size 4

Within NPM, for both ends of the link, I've set Interface Status Polling to 10s, Collect Stats to 1m & Poll for Topology Data ever 30m (I set it to 5m, but it reverted back to 30m after saving).

FWIW, the remote Site object does go red when I shut down the WAN link (I've set the remote office object to get its status from the WAN router at its location).

anyone any ideas?

thanks