Using VB.net to get Excel Cell Value which is not the correct value?

Using VB.net to get Excel Cell Value which is not the correct value?

I've been stuck on this for the past few hours so I really could do with
some help. I am trying to get numeric (integer and decimal) values from an
Excel spreadsheet and use it create a graph on my form using the chart
control or even display that value in a textbox.
The Value of cell A11 is "2003" and K11 is "12.00" but the returned values
are 0 and 12. I use formulas to calculate the rest of the y values. The
strange thing is that text works fine. Cell A3 has "initial" which comes
back as "initial", it's just the numbers which don't work.
xlApp = New Excel.Application
xlWorkBook = xlApp.Workbooks.Open("C:\File.xls")
xlWorkBook = xlApp.Workbooks.Add("C:\File.xls")
xlSheet = xlWorkBook.Worksheets(1)
Dim x1 As String
Dim y1 As String
x1 = xlSheet.Range("A11").Value.ToString
y1 = xlSheet.Range("K11").Value.ToString
MsgBox(x1)
Thanks in advance