Wordpress custom plugin gives error

Question

I added submenu and admin pages on wordpress custom plugin. But it gives an error.

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'wstock_variation' not found or invalid function name.

 add_menu_page('Elites-StockManager', 'Smart Stock Manager', 'export', 'wstock_api_settings', 'wstock_api_connection_settings', '', 7);
    add_submenu_page( 'Elites-StockManager', 'Smart Stock Manager', 'export', 'administrator', 'wstock_variation', 'wstock_variation',8 );

Answer 1

It seems that your function wstock_variation not exists or is created in PHP file not include in your plugin...

If you are using OOP, for example your code need to be like:

add_submenu_page( 'Elites-StockManager', 'Smart Stock Manager', 'export', 'administrator', 'wstock_variation', array($this, 'wstock_variation') ); // remove number 8, method accept only 6 params

$this is method is not static, in case of static method you need to change by class name.