With the release of Opposing Fronts, Company of Heroes was drastically changed. Even if you didn't buy OF, you had to download a massive patch to allow you to play against the new armies. With this patch came loads of changes breaking nearly all mod functionality.
Finally, after months of agony, the first patch to update Europe In Ruins to work has been released. This patch is to be considered very 'alpha' and only updates the mod to work with OF. The new armies will be incorporated in the future.