My drawing tablet doesnt occupy the whole screen?

Ok, so I have a Wacom Bamboo Tablet Model CTH-460. It doesnt have any problem, even in Photoshop and Paint Tool SAI. but when I used it in Manga Studio EX, the mouse pointer seems to occupy only a small space in the left top corner of my whole screen. It works perfectly fine with other software but it doesnt work well with Manga Studio. I remember my brother used it once with Manga Studio and it doesnt have any problem. Now that I am the one who`s gonna use it, it doesnt work anymore. I already tried removing preferences in the Preference Utility, but nothing changed. Is there a problem with my tablet? or maybe I changed the settings accidentally in Manga Studio, that`s why its not working well with my tablet? Can anyone help me fix this problem?