What SD card can I use with Tom Tom One

[Bazz]

I think I have a four or five year old One second edition and have just bought the map upgrades. These would not fit onto the SD card that came with the unit. I have tried putting in another SD card from a camera (cleaned and formatted) and loading the new map. The upload said it was successful but there is nothing on the unit according to itself.
Am I bound into only using a Tom Tom SD card that I wil need to buy from them? Or am I missing something here/doing something wrong?
Cheers.

 

[dhn]

This guide may assist:

Using a memory card for additional maps