Did you place it on the card in Garmin root folder named gmapsupp.img? i.e.: x:\Garmin\gmapsupp.img. [also recognised as gmapsup1.img with latest firmware in 2x5 series]. I have both the original image and the PC Install bat file version, both work fine. Neither the original img file nor one compiled yourself with MapInstall will have an MS Flag of 0 [zero], so you need change it to from 1 if you want to see it in BaseCamp.
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Here's my known-good file [with MS Flag 0]: