__soapCall is returning nothing

I've got the following function:

public function query($sql)
{
    $query = array(
    "queryString"=>$sql
    );
    $queryWrapper = array(
    "query"=>$query
    );

    try {
        $result = $this->_client->__soapCall("query", $queryWrapper, null, $this->_header);
    } catch (SoapFault $e) {
      $this->_client->__getLastResponse();
    }
    return $result;
}

The problem is that I can use var_dump('anything');exit; before the __soapCall(), and I see 'anything'. But if I var_dump('stuff');exit; AFTER the __soapCall(), I get just a blank page. I var_dump('something');exit; in the catch, but I don't see that. It's still just a blank page. My question is, what could be causing this? I would think that if the table in my query didn't exist, or something was wrong with my query at all, I'd get some sort of error. But I'm getting absolutely squat all.

from __soapCall is returning nothing