Class function calling another function in class

Hi all, Not sure if I am doing this right and I can't figure it out, was hoping someone here can help. I have an organization table in mySQL. Pretty standard. My first function getDepts() is working as I intend and returning the tree just as I like it. The new piece I added in there that is not working now is the call to getPositions() within the first function. What I am trying to do is once I get a Department, I want to loop through the Positions table and get the positions that are under that Department. This code goes haywire and loops for ever printing a huge list to the screen. Eventually I need to return this data not to the screen but into an array. Anyone see what I might have wrong in my logic? I have a class and it contains these two functions.

    function getDepts ( $parent = 0, $level = 1 ) {
        $sql = 'SELECT BudgetedOrganization.* ';
        $sql .= 'FROM BudgetedOrganization ';
        $sql .= 'WHERE BudgetedOrganization.boSuperiorOrgID = ' . $parent;

        $rs = $this->retrieveData($sql);
        if ($rs)
        {
            while($row = mysql_fetch_array($rs)){
                $num = 1;

                while ($num <= $level) {
                    $this->str .= "\t";
                    $num++;
                }
                $this->str .= $row['boOrgID'] . ", " . $row['boOrgName'] . "\n";

               // just added this and it ain't working
                $this->str .= $this->getPositions($row['boOrgID']);
                $this->getDepts($row['boOrgID'],$level+1);
            }
        }
        return($this->str);
    }

    function getPositions ( $org = 0 ) {
        $sql = 'SELECT BudgetedPosition.* ';
        $sql .= 'FROM BudgetedPosition ';
        $sql .= 'WHERE BudgetedPosition.bp_boOrgID = ' . $org;
        //echo $sql;
        $rs = $this->retrieveData($sql);
        if ($rs)
        {
            while($row = mysql_fetch_array($rs)){
                $this->str .= " - " . $row['bpPositionID'] . "\n";
            }
        }
        return($this->str);
    }

Later.... $depts = $org->getDepts(); echo "<pre>" . $depts . "</pre>"; Thanks, Charles