Problems sometimes when importing songs

[Dwdrake2]

I had deleted the troublesome folders prior to this but it still wouldn't up load them, So I deleted my whole data base and re imported the folders I was having trouble with. One folder had 375 songs found but only 225 were listed as new songs added. another folder had 225 songs found but only 150 were added. Why didn't the software see these songs before deleting the whole data base? I'm more confused than ever??

Edit: Also Im using a Memorex 32x/52x rewrightable Compact disk player to import the disk if that is needed info...