fopen error in uvision3

Hi all

when I run the below program i am getting the error
*** ERROR L128: REFERENCE MADE TO UNRESOLVED EXTERNAL

could any suggest me how to remove the error?

looking for your help
t.senthil

#include <ARTX.h>
#include <stdio.h>
void tst_fopen();

void main()
{
tst_fopen();
}

void tst_fopen (void) {
   FILE *fin;

   fin = fopen ("Test.txt","r");
   if (fin == NULL) {
      printf ("File not found!\n");
   }
   else {
      // process file content
      fclose (fin);
   }
}