You are not allowed to access this URL

Hi,
I get the "You are not allowed to access this URL" Error message on a file upload form. The form works fine for ~small files but files like 20MB are not working.
The "File Upload" settings are: file_uploaded:ppt|pptx|odf{300000-0}, the file upload path is writable. Sometimes I don't get the error message, but the form again with a red "x" Element on top of the form. I set "checkToken" to off and there are no additional <form> tags apart from the leading one in the html site code.
I also tried looking for the main php settings but I'm not able to change them due to provider restrictions (i think, I don't have access to the folder, the joomla php information suggests). Also uploading a file bigger than this setting suggests is possible, but not by much...
I enabled the debug settings, but a debug log is only shown when I try to upload (successful) a smaller file.
Can you help me? Or can you suggest another way to write a file upload form very quickly, as we need it right now?
My specs are: Joomla 1.5.20, PHP 5.2.14, ChronoForms V 3.2.
Thank you very much!

This is the code created by the form editor:

<div class="form_item">
  <div class="form_element cf_heading">
    <h1 class="cf_text">Powerpoint upload</h1>
  </div>
  <div class="cfclear"> </div>
</div>

<div class="form_item">
  <div class="form_element cf_text"> <span class="cf_text">Please upload your powerpoint presentation for the 'Archives on the Web' conference in Vienna 11/2010 using this form.</span> </div>
  <div class="cfclear"> </div>
</div>

<div class="form_item">
  <div class="form_element cf_textbox">
    <label class="cf_label" style="width: 110px;">Speaker Name</label>
    <input class="cf_inputbox required" maxlength="150" size="30" title="" id="text_3" name="speakers_name" type="text" />
  <a class="tooltiplink" onclick="return false;"><img height="16" border="0" width="16" class="tooltipimg" alt="" src="components/com_chronocontact/css/images/tooltip.png"/></a>
				<div class="tooltipdiv">Speaker Name :: Please input you name.</div>
  </div>
  <div class="cfclear"> </div>
</div>

<div class="form_item">
  <div class="form_element cf_fileupload">
    <label class="cf_label" style="width: 110px;">File</label>
    <input class="cf_fileinput cf_inputbox" title="" size="20" id="file_4" name="file_uploaded" type="file" />
    <a class="tooltiplink" onclick="return false;"><img height="16" border="0" width="16" class="tooltipimg" alt="" src="components/com_chronocontact/css/images/tooltip.png"/></a>
				<div class="tooltipdiv">File :: Please select local file.</div>
  </div>
  <div class="cfclear"> </div>
</div>

<div class="form_item">
  <div class="form_element cf_button">
    <input value="Submit" name="button_6" type="submit" />
  </div>
  <div class="cfclear"> </div>
</div>

Hi yngwi ,

You'll need to talk to your ISP. The file upload size limit is set by the hosting configuration, not by ChronoForms.

You might be able to upload larger files using an FTP account, or some kind of Cloud based file system.

Bob

Thanks for your reply. I'll do that. Your software is great, though!