The Paris Metro has expanded and your old map isn't any good any more.
Lines 4, 8, 12, and 13 have added new terminating metro stops at one or both ends. Since the direction you are going on the metro is determined by the final stop, it's important to know the name of the final stop. For example, to go south on the popular 4 line, you will now go towards Marie de Montrouge instead of Porte d'Orleans.
Chances are almost certain the guidebook metro map you have is out of date, since the new map was only published in February 2013. Here's one you can print and take with you. As always, click on the map to bring up a larger copy.
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