PowerShell FTP Files

I am trying to move my files that I back nightly onto a local server to one of my hosted servers.  I have created this file in PowerShell script but am getting the below errors.  The server on the other end is 2K3 running FieZilla.

# locate all backup files
Foreach($File in Get-Childitem "\\ServerName\ServerBackups\SQL\db\" -recurse)
{
      # upload all the files
      
    $ftp = "ftp://username_backup:password@compass.mycompany.com/" + $File
    "ftp url: $ftp"

    $webclient = New-Object System.Net.WebClient
    $uri = New-Object System.Uri($ftp)

     "Uploading $File..."
      $webclient.UploadFile($uri, $File)
}

And here is the error I get

ftp url: ftp://username_backup:password@compass.mycompany.com/backup_201104081800.bak
Uploading backup_201104081800.bak...
Exception calling "UploadFile" with "2" argument(s): "An exception occurred during a WebClient request."
At line:13 char:23
+     $webclient.UploadFile <<<< ($uri, $File)
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : DotNetMethodException
 
ftp url:ftp://username_backup:password@compass.mycompany.com/backup_201104101800.bak
Uploading backup_201104101800.bak...
Exception calling "UploadFile" with "2" argument(s): "An exception occurred during a WebClient request."
At line:13 char:23
+     $webclient.UploadFile <<<< ($uri, $File)
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : DotNetMethodException