xxx.axf: Error: L6218E: Undefined symbol LCD_ClearScreen (referred from rtc.o).

Let me define the problem details.
Each peripheral have a .c file & .h file
Error :- xxx.axf: Error: L6218E: Undefined symbol LCD_ClearScreen (referred from rtc.o).
The function LCD_ClearScreen is well defined in lcd.c file.
I had included lcd.h file in rtc.c
I have used the function LCD_ClearScreen in rtc.c
while declaring extern LCD_ClearScreen also the error occurs.
If function is declared again in rtc.c file it compiles otherwise error L6218E.
How to solve it. The compiler is KEIL

is .c file included in the project for build? can you post a screenshot of project explorer window where all files in project are listed?

Yes they are fine. I have included everything. Unable to post screen shot coz. there are more than 25 .c & .h files.

Ok then, check if you did not mention "LCD_ClearScreen" as a static function in your lcd.c file.

thanks for your help.