I was asking one of my friends Ebeid - who works as a Developer Support Engineer at Microsoft Regional Developer Support Center - about the strangest case he had ever experienced in .NET. The answer was very strange and astonished me; simply stated, the problem was "9.6 - 9.4" is not always equals to 0.2 :). I try it and it gives me 0.199999999999999. I searched about this a lot and I didn't find anything with a good benefit except this forum post at MSDN social network.
The reason for this problem is that some floating point numbers cannot be precisely represented in binary, ust like 1/3 cannot be precisely represented in decimal.
To solve the problem use FormatNumber or formatCurrency functions which allows you do some quick rounding and manipulation of your output.
Take care next time when you subtract two decimal numbers :)