功能错误（致命错误：函数名称必须是字符串）

<?php
    require_once('includes/auth.php');
    function getMarkets(){
        $count_markets=querydb("SELECT count(*) as marketcount from markets ");
        $result=$count_markets('marketcount');
        return $result;
    }

I have the above code and i am getting the error below:
Fatal error: Function name must be a string

$result=$count_markets('marketcount'); - remove $ from count_markets.

Seen the Error was using $count_markets('marketcount'); instead of $count_markets['marketcount'];