error

hi sir
iam excuting this program in keil 51;

#include <math.h>
#include <stdio.h> /* for printf */
#include<reg51.h>

void tst_sqrt (void) {
float x;
float y;

x = 25.0;
y = sqrt (x); /* y = 5 */

printf ("SQRT(%f) = %f\n", x, y);
}

while doing this one Iam geting this errer

TO "ex3.c"
*** FATAL ERROR L210: I/O ERROR ON INPUT FILE:
EXCEPTION 0021H: PATH OR FILE NOT FOUND
FILE: C:\KEIL\C51\LIB\C51FPS.LIB
Target not created

why this error was comeing

regards