Unknown Column Error On TRIGGER

Question

I have created a trigger in my MySQL database, which is meant to set the column named "gps_coordinates" to equal the column named "previous_gps_coordinates" before updating it with the new values.

The problem is on testing, I get the following error message:

Error Code: 1054. Unknown column 'gps_coordinates' in 'field list'

My table structure is as follows:

|Location Number| gps_coordinates | previous_gps_coordinates
|105285         |Value can be NULL| Value can be NULL
|125896         |Value can be 0   | Value can be 0

My Trigger is the following:

DELIMITER $$

CREATE TRIGGER GPSUPDATE
BEFORE UPDATE 
ON sys_reference.location_reference
FOR EACH ROW 

BEGIN   
IF NEW.previous_gps_coordinates >= 0 THEN   
SET NEW.previous_gps_coordinates := gps_coordinates;    
END IF;
END$$
DELIMITER ;

I have also tried the variation of:

DELIMITER $$

CREATE TRIGGER GPSUPDATE
BEFORE UPDATE 
ON sys_reference.location_reference
FOR EACH ROW 

BEGIN   
IF NEW.previous_gps_coordinates IS NULL THEN    
SET NEW.previous_gps_coordinates := gps_coordinates;    
END IF;
END$$
DELIMITER ;

Any help will be appreciated here. Thanks