Failed to open /dev/uart_0

Hello,

I am using Quartus II 4.2 and Nios II Development kit 1.1.

When I try to run a code (I wrote to read from uart_0 and write what it read to uart1) as Nios II Instruction Set Simulator. I obtain th following:

"Failed to open /dev/uart_0".

Thanks in advance,

Julia