I don't understand the bit below - you seem to be doing a lot of unnecessary calculations and conversions
 

stDate = CDate(.Item(3).ToString) ' this is a date stored in a database being converted to date
                dtDate = DateTime.Parse(stDate, Globalization.CultureInfo.CreateSpecificCulture("en-CA"))
                amount = DateDiff(DateInterval.Day, Now, dtDate) * fratepday


Just post the entire code block where you retrieve the data from the database and what calculation you are doing and tutakusaidia.

Also, you are using the Timespan wrongly. The documentation is here http://msdn.microsoft.com/en-us/library/system.timespan.aspx

The property you want is Days so 

Textbox.Text = MyDifference.Days