Cant add expense

Hello,

I get below error when I try to add expense from API:

[errors] => stdClass Object
(
[error] => stdClass Object
(
[message] => Expense or expenses data required
)

    )

Below is my code:
$vdata=array(‘user’ => ‘https://api.freeagent.com/v2/users/308553’,
‘description’ => ‘hello’,
‘dated_on’ => ‘2011-08-24’,
‘category’ => ‘https://api.freeagent.com/v2/categories/287’);

print_r($client->post(‘expenses’,$vdata));

Can anyone know why is this happening ?

Thanks,
Kanaji.