Kata, I'm not sure what versions of Word and MathType you are using, but I was able to successfully create the MathPage with MathML. I am using Word 2013 and MathType 6.9. This is the page I created: http://dl.dropbox.com/u/17008533/187.xht
Not sure what could have gone wrong with yours. It does seem that you chose an appropriate "target" for the MathPage; it looks like you chose XHTML+MathML.
If you can give me some more details about what steps you're taking from start to finish, I'll try to help more. Also let me know what versions of the software you're using.