How to convert values in Datagridview from String to Double?

Question

I have a calculated column in datagridview when I am trying to use the data from that column to calculate another parameter, I am getting an error as "Converting from string to Double is not valid" 

 

How can I convert the values to double? Thanks so much for your help!

 

Here is what I was trying to do, but does not do anything! 

 

   

Convert.ToDouble (Data1.Rows(i).Value.Cells(10).Value)

 

and also tryied this command as well, not working...

 

    

Dim S As Double = 0
    Double.TryParse(Data1.Rows(i).Cells(10).Value, S)