tieronline wrote:

In the demo I see a PDF button. This is missing in my installation.

How can I activate it?

Soved - i didnt install the DomPDF


Installing DomPDF library (for creating PDF for invoices)

Download the file dompdf.zip from My Downloads
Unzip the file. You should obtain a folder called /dompdf
Copy that file into /components/com_invoices/helpers/ folder
The resultant folder should be /components/com_invoices/helpers/dompdf/
Make sure you are running PHP 5 or greater (otherwise DomDPF will not run)
Make sure your PHP directive MAGIC QUOTES is set to OFF (otherwise DomPDF may encounter problems)
Create a new folder in the root of your Joomla installation, and name it "pdfinvoices". This is necessary in order to be able to attach PDF invoices when you send email invoices.