You can find detailed instructions for installing and solving the main problems (if your iPod does not see the card through iFlash) - on the manufacturer's website indicated on the board.
Top popular reasons: fake SD card, incorrect formatting of the card, incorrect restore of the iPod (software problem), problem with the HDD ribbon

Please check your model against this compatibility list before ordering:
* iPod 5g Video 30Gb ~2 000 Tracks
* iPod 5g Video 60Gb ~5 000 Tracks
* iPod 5.5g Video 30Gb ~20 000 Tracks
* iPod 5.5g Video 80Gb ~50 000 Tracks
* iPod 6g Classic 80Gb - 128gb cards, ~50 000 Tracks
* iPod 6g Classic 120Gb, 160Gb 128gb cards, ~50 000 Tracks, may be Requires Ribbon
* iPod 6.5g 120Gb - 128gb cards, ~50 000 Tracks
* iPod 7g Classic 160Gb (late 2009)
* iPod 6th Gen 160Gb (Thick) model will require a replacement HDD Ribbon as the original hard drive uses an CE-ATA interface, replacement Ribbons must be purchased separately

The track limit's shown are only approximate, the actual limit will depend on your iTunes library and the amount of meta-data stored within (e.g. artist name, track name, genre, comments, album art, etc, etc).
The track limits are a function of the iTunes database size and the memory (RAM) on the iPod motherboard, it is not a limitation of the iFlash adapters.