nios appl programs

Hi

Iam trying to control the UART , PIO(led's and seven seg disp) ,etc through c-application programs in the nios IDE. I have included the "excalibur.h" include file which contains inf about memory map of the peripherals , default functions ,etc. Now when iam trying to send any character using the function "nr_uart_txchar(int c, np_uart *)" it's showing an error as "undefined reference to nr_uart_txchar()" .This is the problem even with other functions like: "nr_delay()", "nr_uart_rxchar()",etc. None of the default functions are getting executed. But iam able to use the data structures like np_pio_data,etc and iam also able to set the direction and also interrupt priorities,etc .The problem comes only with the functions.

Can someone help me out of this problem??????