Eager loading in Laravel returns empty array

I started using the eager loader in Laravel 4.

I have two tables (campaigns and reports) whit following relation in the Campaigns Model:

public function reports() {
   return $this->hasMany('Reports', 'account_id', 'adwords_id')->select('CLICKS', 'COST');
}

I had to use non-conventional column names here unfortunaly.

When I now do:

$data['campaigns'] = Campaign::get();
foreach ($data['campaigns'] as $campaign) {
  print_r($campaign->reports);
}

it outputs all the reports for the campaigns the way it should.

But now I want to eager load this:

$data['campaigns'] = Campaign::with('reports')->get();
foreach ($data['campaigns'] as $campaign) {
   print_r($campaign->reports);
}

This outputs me just empty arrays.

What am I doing wrong? I really want to use eager to have fasters scripts...