As already suggested by LucaMS you need to improve the layout.
Be aware that TextSize is density independant !
So setting it proportionally to teh view height works only with a density of 1 !
When using pixel values you must use dip values.
To check why the "." doesn't work well put a breakpoint in the code and go through it step by step.
When you post a project post it as a zip file (IDE menu File / Export As Zip).
PS From the comments above, you may want look creating buttons etc with an external graphics program. If you have any experience with the likes of Photoshop, Gimp is a good free alternative but a steep learning curve. Paint.net at Download.com is an easier start.