Using __attribute__((at(address)))

Hi,

I hope someone can shed a light on this, I have a board
with a LCP2294 and 4Mb IDT71V416L external RAM.

Using Keil RealView 3.01 I used the "__at 0x81000000"
modifier to place a global var at a specific location
in the off chip RAM.

Using __attribute__((at(0x81000000))) with MDK-ARM
4.0 it does not work. The project compiles without
any errors, but the contents of the variable are
undefined, even after assigning a value to that var.

Does any one had any problems related to this issue ?

Thanks in advance
Paulo