Target not created error in Keil software, please help to solve this issue.

Build started: Project: secondpasw
Build target 'Target 1'
compiling paswd.c...
linking...
BL51 BANKED LINKER/LOCATER V6.22.2.0 - SN: Eval Version
COPYRIGHT ARM Germany GmbH 1987 - 2017
".\Objects\STARTUP.obj",
".\Objects\paswd.obj"
TO ".\Objects\secondpasw"
PRINT(".\Listings\secondpasw.m51")
*** FATAL ERROR L210: I/O ERROR ON INPUT FILE:
EXCEPTION 0021H: PATH OR FILE NOT FOUND
FILE: .\Objects\paswd.obj
Target not created.
Build Time Elapsed: 00:00:03

I added my startup .51A to my source file in my project 

-----below is my code------------

#include<reg51.h>
#include<String.h>
#define keypad P1
#define lcddata P2

sbit rs=P3^0;
sbit en=P3^1;
sbit relay_drive_in=P3^2;

char psw_in();
void delay(unsigned int x);
void lcd_cmd(unsigned int cmd);
void lcd_data(unsigned int d);
void lcd_str(unsigned char *str);

unsigned int s=0;
unsigned int def_pasw=4444;
unsigned char z_arr[5];

void main(void){

while(1){
delay(20);
relay_drive_in=0;
lcd_cmd(0x30);
lcd_cmd(0x0C);
lcd_cmd(0x80);
lcd_str("Enter password");
z_arr[s]=psw_in();
lcd_cmd(0xC0+s);
lcd_data('*');
s++;


if(s==5){
unsigned int y;
lcd_cmd(0x01);
lcd_cmd(0x80);
y=strcmp(z_arr,def_pasw);
if(y==0){
lcd_str("correct password");
relay_drive_in=1;
}
else{
lcd_str("wrong password");
relay_drive_in=0;
}
}
}


}

void lcd_cmd(unsigned int cmd){
lcddata=cmd;
rs=0;
en=1;
delay(20);
en=0;
}

void lcd_data(unsigned int d){
lcddata=d;
rs=1;
en=1;
delay(20);
en=0;
}

void lcd_str(unsigned char *str){
unsigned int i;
for(i=0;str[i]!='\0';i++){
lcd_data(str[i]);
}
}

char psw_in(){
unsigned int psw;
keypad=0xFE;

if(keypad==0xEE){
psw=1;
}
else if(keypad==0xDE){
psw=2;
}
else if(keypad==0xBE){
psw=3;
}

keypad=0xFD;

if(keypad==0xED){
psw=4;
}
else if(keypad==0xDD){
psw=5;
}
else if(keypad==0xBD){
psw=6;
}

keypad=0xFB;

if(keypad==0xEB){
psw=7;
}
else if(keypad==0xDB){
psw=8;
}
else if(keypad==0xBB){
psw=9;
}

keypad=0xF7;

if(keypad==0xE7){
psw='*';
}
else if(keypad==0xD7){
psw=0;
}
else if(keypad==0xB7){
psw='#';
}

return psw;

}

void delay(unsigned int x){
unsigned int i;
for(i=0;i<x*1000;i++);
}