add_rewrite_rule parameter is not received by the page

This doesn’t work:

add_rewrite_rule('^spor/?','index.php?pagename=search&search_text=spor',top);

It goes to the search page but search_text=spor is not taking effect. (Like Empty)

When I manually browse from browser:

www.mydomain.com/index.php?pagename=search&search_text=spor

the query works succesfully. What am I missing?

Custom query vars have to be added via the query_vars filter to be parsed within rules.

function wpd_add_query_vars( $qvars ) {
  $qvars[] = 'search_text';
  return $qvars;
}
add_filter( 'query_vars', 'wpd_add_query_vars' );

You can then get the value with get_query_var('search_text').