There is absolute no problem with the formula or syntax. Now question is where are you using this function(in which object), thats matters.
I have created few rows of sample data and tried that function, it gives output without any problem. See the attached Qlikview document.
I have used this function in Chart but it will not work in Text object. As it will give multiple result and text box shows only one value. Please share some more details about it.
