I ended my wordpress theme, which called the_mdttheme.

I tried to check it and get two errors with translation in comment_form().

Can’t understand what did wrong, can someone help me? Here is two warnings:

WARNING: Found a translation function that is missing a text-domain. Function _x, with the arguments ‘Comment’, ‘the_mdttheme’

WARNING: Found a translation function that is missing a text-domain. Function _x, with the arguments ‘Comment *’, ‘the_mdttheme’

Here is my code, warnings are inside 'comment_field':

$args = array(
    'comment_field' => '<p class="comment-form-comment"><label class="hidden" for="comment">' . _x( 'Comment', 'the_mdttheme' ) . '</label><textarea id="comment" name="comment" cols="45" rows="8" aria-required="true" required="required" placeholder="' . _x( 'Comment *', 'the_mdttheme' ) . '"></textarea></p>',
    'submit_button' => '<div class="form-submit-wrapper"><input name="%1$s" type="submit" id="%2$s" class="%3$s" value="%4$s" /></div>',
    'label_submit'  => __( 'comment', 'the_mdttheme' ),
);
comment_form($args);

Thanks in advance!