Blank screen when open URL consultation Quote


I’m running InvoicePlane 1.4.6 and when I go to Quote > Consultation > Send by email, I have on the bottom of the page a link to view the quote online.
But when I click on it, I have a blank page, without error.

What’s wrong ?

As mentioned in the FAQ (that should have been read before posting) you should help us with debug information:

I had activate the log as described on the FAQ, but the application/logs/ directory is always empty (there is only the index.html file).
The apache log are not saying anything except this :

78.xx.yyy.zzz - - [31/Mar/2016:17:38:37 +0200] "GET /index.php/guest/view/quote/JrZWBXjeEgwHDrT HTTP/1.1" 200 20 "" "Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0"