SOAP and nested input

Hello!

If I need to pass nested input to a SOAP function; For example a 
function that requires these parameters:

<foo>bar</foo>
<foonest>
    <barnest>foobar</barnest>
</foonest>

Should I simply nest two arrays to the php soap function, i.e:
$client->foo(array("foo" => "bar", "foonest" => array("barnest" => 
"foobar"));

'm having some trouble with a SOAP server, and I'm not sure if I passed 
the params incorrectly or something else is wrong.

The exception I get is: Catchable fatal error: Object of class stdClass 
could not be converted to string.

Thanks for your time!

Regards Emil