Please help

[padcaz123]

I have recently installed an airport express, in my house i have 2 iphones, 2 ipads 2 pcs and an Imac, they are all working correctly on wifi with the exception of 1 ipad, which for some reason has an IP address starting 169, it works in other wifi areas but not on my home network, i have tried resetting it, resetting the network on the ipad, but it still comes back with 169, i have no idea what to try next
PLEASE HELP
Thanks
Jason