Hello Raheleh,
since your question is not very clear (as OriginalGriff already commented on) I'll just post what I found out by trying out your mask:
This mask won't allow for any input since the decimal point in a mask is just a placeholder for whatever character the decimal seperator is in your current Culture and the "/" is the placeholder for whatever the date separator is in you current Culture. If you want to escape a mask character from it's special meaning you'll have to put a \ in front of it.
If you're looking to input numbers use something in the likes of:
#0.00\/#0.00\/#0.00
This will allow you to enter up to two digit numbers with two decimal places where numbers from zero to nine won't have to be prefixed with a zero, but both decimal places have to be entered. The numbers will appear to be separated by a forward slash:
http://msdn.microsoft.com/en-us/library/system.windows.forms.maskedtextbox.mask(v=VS.80).aspx
Best Regards
Manfred
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