loading a 2004 Navteq France CD into RT3

[macR]

Hi There
I am a total Newbie to this site so sorry for dropping any clangers, have viewed the site and found some very good info.
Being totaly novice to Sat nav, RT3 unit tech etc, got to start somewhere.
We have a peugeot 307 sw 2004 with a RT3 unit built in with the Sat nav. The sat nav unit has a 5.45 version found this out from the forum thanks. It plays our Navteq 2004-2005 Great Britain with MRE CD fine. We are off to france this year so got given a copy of a friends Navteq 2004 -2005 France cd with mre. I took our great britain cd out and inserted this France CD and the unit said on the screen navigation cd not loaded. Help !!! what do we do now, a bit unsure what to do. We are only going to France for 2 weeks and usually travel the smaller roads so do not need to upgrade as the roads do not change that much. Also my missess has warned me not to "bugger" up her car system, and we can use a Map to get by in France. Any advice for a total novive in this field would be a real "mercie" and thanks.