Getting trying to get property of non-object error

Good Morning - once I change the sql statement to query from the database in my codeigniter model file and display the result and do something - the change in statement does get what it should and does what it should - displays correctly in table

However, 1 of the feature on that page in my cms stops working - the problem is the cantonese characters (obtained from database) in a drop-down menu cannot be displayed - it is displaying some strange and unwanted characters

Also, there are so many:"trying to get property of non-object " boxes displayed before I can scroll down to the result of the cms page

Please tell me what could the possible reason be and how could I solve it. It is really urgent. I am just a beginner in web and php. Thank you very much.