Gridview Trim Error in ASP.NET

This is my reference question; String.Format Same Code Different View

When i try this code;

var cultureWithoutCur开发者_Go百科rencySymbol =
        (CultureInfo)CultureInfo.CurrentCulture.Clone();
            cultureWithoutCurrencySymbol.NumberFormat.CurrencySymbol = "";
            GridView1.FooterRow.Cells[9].Text = String.Format(cultureWithoutCurrencySymbol, "{0:c}", sumMV).Trim();

I gettin an error like this;

How can i solve this problem? Is it something wrong in my code?

Since you want currency without symbol why don't simply use:

sumVM.ToString()