Android :: Error Using A Custom Text For Alert Dialog

My requirement was to invoke a alert dialog with a string text that gets modified dynamically when the user hits a button every time
for example:
string str="you have clicked "+ count + "times";
where count is an integer variable that gets incremented every time the user hits a button. and when i assign this string to the text of an alert-dialog ,i get the alert-dialog at runtime but with an empty text value...ie. a naked alert-dialog with just OK cancel button.