使用数组中的行号将自定义样式设置为Laravel Excel工作表

I have a loop building an array that I'm dumping to excel and I've created an iterator that counts the rows I want and adds them to ```$boldRows`` array. This is so that I can get the rows I want to set custom styles, in this case Bold lettering.

So I have the row count from my data, then I build my sheet from the data array $allgroupResult.

The sheet prints out perfectly as far as data is concerned but it's not setting my $boldRows to bold font.

What am I doing wrong?

$boldRows = array();

$name = ' Export For:' . $id;

$build = Excel::create($name, function ($excel) use ($allgroupResult) {

    $excel->sheet('Export', function ($sheet) use ($allgroupResult) {

        $sheet->fromArray($allgroupResult);

        foreach ( $boldRows as $row )   {
            $cell_name = excelColumnFromNumber($row)."1";
            $sheet->getStyle( $cell_name )->getFont()->setBold( true );
        }
}