Error when compiling code for Arduino Nano, 4.2in screen.

[richterlevania3]

/home/terminusest/Arduino/epd4in2_V2/epd4in2_V2.cpp:498:6: error: prototype for 'void Epd::Set_4GrayDisplay(const char*, int, int, int, int)' does not match any in class 'Epd'
 void Epd::Set_4GrayDisplay(const char *Image, int x, int y, int w, int l)
      ^~~
In file included from /home/terminusest/Arduino/epd4in2_V2/epd4in2_V2.cpp:28:0:
/home/terminusest/Arduino/epd4in2_V2/epd4in2_V2.h:67:10: error: candidate is: void Epd::Set_4GrayDisplay(const unsigned char*, int, int, int, int)
     void Set_4GrayDisplay(const unsigned char *Image, int x, int y, int w, int l);
          ^~~~~~~~~~~~~~~~
/home/terminusest/Arduino/epd4in2_V2/epd4in2_V2.cpp: In member function 'int Epd::Init_4Gray()':
/home/terminusest/Arduino/epd4in2_V2/epd4in2_V2.cpp:213:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

Using library SPI at version 1.0 in folder: /home/terminusest/.arduino15/packages/arduino/hardware/avr/1.8.6/libraries/SPI 
exit status 1

Compilation error: prototype for 'void Epd::Set_4GrayDisplay(const char*, int, int, int, int)' does not match any in class 'Epd'

[shhds]

To repair