"The upload path does not appear to be valid"

[eluser]ellipsis[/eluser]
Another user in a similar thread on the CI forums suggested to vardump the path to see if the server can see it.

Code:

var_dump(is_dir('./uploads/files/');

and I get bool(true), so I guess the path is fine...
I also tried the code that I eventually want to use to create a subfolder for each user, using their id number.

Code:

$upath='./uploads/files/'.$this->session->userdata('uid').'/';
    var_dump(is_dir($upath));

this also returned bool(true).

Any ideas?... any? I'd try making the upload form, but frankly I don't even know how in CI.