APEX: apex_application.g_print_error_message problem

When i'm using this command

apex_application.g_print_success_message := '<span style=开发者_开发百科"color:GREEN">Message</span>';

to show success message is works fine

but when i used the error command apex_application.g_print_error_message it gives me this error, anyone can help-me

ORA-06550: line 10, column 20: PLS-00302: component 'G_PRINT_ERROR_MESSAGE' must be declared ORA-06550: line 10, column 3: PL/SQL: Statement ignored

apex_application.g_print_error_message is a variable, so you can set it to a value like '<span style="color:GREEN">Message</span>' but you can't execute it as a "command".

No apex_application.g_print_error_message is available, only apex_application.g_print_success_message is.

Can try apex_error package. See Using APEX_ERROR to manage custom error messages.