i cant upload any thing except picture

[eluser]Sara rad[/eluser]
Last night i change my controller to this :

Code:

// Set upload rules for screen
$config['upload_path'] = 'files/shop/';
$config['allowed_types'] = 'jpg|png|gif';
$config['max_size']    = '200';
$config['max_width']  = '1024';
$config['max_height']  = '768';

// Set upload rules for source
$config['source']['upload_path'] = 'files/shop/source/';
$config['source']['allowed_types'] = 'rar|zip|psd|cdr|ai';
$config['source']['max_size']    = '24000';

// Select random name
$data['art_saved_name'] = $this->send_art_model->select_rand_name('arts_for_sell');

// Set name for saveing file
$config['file_name']  = $data['art_saved_name'];
$config['source']['file_name']  = $data['art_saved_name'];

// END OF RULES SETTING --

// Load Upload Library
$this->load->library('upload',$config);

if( ! $this->upload->do_upload(array('screen','source')))
{
    echo $this->upload->display_errors();
}

and now script dont upload anything and show this warning :

Message: Illegal offset type in isset or empty

Filename: libraries/Upload.php

Line Number: 146

and file uploading library show this errors :

The upload path does not appear to be valid.

You did not select a file to upload.

But path is valid and i select a file .

i know my code is wrong , I hope you help me :x

thanks