@Anonymous User
Is the box a fair distance away from your router? Could be that the box is getting a poor signal, resulting in it not downloading the app properly. Make sure the box is in an open space, not tucked behind or under the TV, or on a crowded shelf. Sometimes moving the box from one side of the TV to another may help, or a different place one room, cables permitting. Also if you have the black NOW TV box, connecting via an Ethernet cable would help, although this often isn't practical if the router isn't nearby. It's also possible that changing the wifi channel on the router may help (if it's set on auto then rebooting the router should make it select the current best choice).
If this doesn't seem to help, or you know the box is getting a strong reliable signal, try a hard reset of the box. Wiith the box powered up insert a pin or bent paper clip into the reset hole at the rear and hold in until you see the box reset. You will need to re-enter your wifi and NOW TV account details afterwards. The BBC iPlayer app will be downloaded as part of the reset process.
