Tracking code not found


Hallow Everyone,

Piwik seems to be just what we need so I am keen to get it working.
The installation of Piwik went smoothly and also I installed nfrPiwik on our Joomla site and copied the tracking code into the area provided. So far so good.
But when I go into the administration are of our Piwik installation I get the message/page that I need to install the tracking code. Which I thought I had done (with nfrPiwik).
The only thing is that I installed nfrPiwik before installing Piwik and am wondering if this has confused nfrPiwik(?)
Any tips on how to clear this problem would be a great help.
Alan Searle
Cologne, Germany