actually there is just one option that's "City Navigator Singapore/Malaysia NT MAP 2011.20" and infront of it ,is unlock button when I press that, it says "The connected device does not qualify for the update"

first u must comfirm your nuvi is local set sg/my firmware.
I can update navteq maps every time but your nuvi should be local set for support JV.
1) Don't x2 clicks the install to install the maps. extract the installer.
2) After extract the installer u got many file.
3) Go to mapdata folder to copy the gmapprom to your nuvi device. Delete the old gmapprom first.
4) Go to mapdata-JV folder to copy SgMyNav.jcv to your nuvi device JCV folder. Delete old SgMyNav.JCV first
5) U should create a gmapprom.unl. U should got the unlock id first at the garmin.sg website.
6) the copy and paste the id at notepad, then save as gmapprom.unl
7) copy to the gmapprom.unl to the garmin device same place with gmapprom.img
maybe u cannot download the navteq maps at the garmin.sg website, u can got it at other website go to google search
Garmin City Navigator Sg/My NT 2011.20