SCANF

I am using lpc2919 board and using ARM REAL VIEW compiler and i face
the following problems when i use scanf() statement to get values
from serial.

I have included the Retarget.c file as follows

struct __FILE { int handle; /* Add whatever you need here */ };
FILE __stdout;
FILE __stdin;

int fputc(int ch, FILE *f) {
return (sendchar(ch));
}

int fgetc(FILE *f) {

return (sendchar(getkey()));
}

The printf statement works fine with UART1, but when i use the scanf
() in my routine i get the following error

Error:L6218E: Undefined symbol __backspace (reffered from__0scanf.o).

I could not find the error in keil help menu.

But when i comment the scanf() in my routnie i dont see any errors
like that.What hould i include or configure so that scanf() works on
my REAL VIEW ARM compiler. Can anyone send a example code with scanf
() routine which reads the input from keyborad.

With regards
-Gerardo Diez