myform_validate() and myform_submit() functions not responding
1 . You can add how many submit handler you want by using this

 $form['actions']['submit']['#submit'][] = 'mymodule_what_ever_function';


if you want to add a submit handler after default submit handler one callback the next callback to be called you can use this, This submit handler will be called after submit call back.

form['#submit'][1] = test_function;


To unset submit handler

submit handler

unset($form["actions"]['submit']);



$form['#validate'][] = 'test_validation_function'; 

function test_validation_function($form, $form_state) {}



this function will call before submitting the result. 

Add these handlers and once clear your Drupal cache 

Still you face issue look in to this url for example will help you out 

https://www.drupal.org/node/717740