Just got a new GT-31 and thought I would be able to use a Canon SD card but when I try to insert it I can't shut shut the cover. I insert it with the label on the card facing towards the back of the GPS. I push it down and it seems to click into place but the cover won,t snap shut. If I reverse the card it does not stay clicked down. I have been unable to find any definitive instruction as to which way it should go and I don't like to put too much pressure on the cover. The card is labeled Canon MultiMediaCard-16M. Maybe its unsuitable??
I find with mine (GT-11) you have to push the card quite far in to get it to click properly. I had to use the nail on my thumb to get it all the way in and when it is in properly it shouldnt stick out at all. I had trouble with this at first too but once you get it the first time its easy.
Bubs
G'Day Herb.
I'm fairly sure the 31 and 11 are the same card wise. With my GT11 the card label faces up, and goes all the way into the slot, there is nothing sticking out to jam the cover.
Are you sure it's an "SD" card???
Apart from that there is also the issue of card voltage, I'm not sure that the cannon card is compatible, there is a list somewhere of what will work, I'll see if I can find it.
Hey Herb, the card I use with my GT11 is a SD card, I don't know but I think a MMC card is different 
Or maybe the new GT31 takes a MMC card also now
Someone smarter than us will know 
Edit
just beat me decrepit, you must use more than two fingers typing.
i think bubs is right- the card, if properly inserted ,should be perfectly flush with the top of the slot it sits in,i think the mmc should be the same dimensions as the sd card as well
OK here's what the locosys site says.
GT-31 provides power of 2.8VDC.
---------------------
The following cards have been tested to work with GT-31:
SanDisk 2G
Transcend 1G
Kingstone 2G
PNY 2G
PQI 2G
Apacer 2G 60X
Compatible/Suggested SD card to go with Locosys GT-31/BGT-31 or SD cards (<=2GB) with 2.8VDC(3.3VDC~2.7VDC) power input should work.
--------------
I have a sandisk 1gb in mine
Thanks for all your replies...They say use a SD/MMC card I have both and they look exactly the same.
When the time came to insert the card I was not sure which way was correct(whether the label should be up or down) I found a illustration which seems to indicate that the tapered corner should be close to the USB port. In this way the card would go in but did not click home. I turned it over and the card went and clicked but the cover would not close. i tried it a couple of times and then found a DSE card marked SD 60X. This just behaved the same.
This morning i inserted a card with the tapered corner to the USB and it will go right in but I have to use a sharp instrument to get it to come out. It will not go in the other way.
Which way should the Tapered Corner go??? I am thinking that my GPS may be going to Tawain.
Well Ok....Everything seems to be right now.
Thanks to everybody for their help....I think Bubs was spot on when he said that it takes a bit of pushing the first time or two.
The trip to Tawain has been cancelled...all I have now is get my head around the rest of it. No need to hurry much because the fishermen are pretty happy with the forecasts.
If in doubt, ask a young fella, thanks Bubs 
Herb, if you have any set up probs, ring me mate.
