Problem with extension method with asp.net web form page code behind

Question

i am creating an extension method to check null datarow with c#, i am trying to use the extension method in my asp.net web form code behind but giving me that the method IsEmpty doesnot in the current context here is the code i am trying

 public static class IsNullValidator
    {
        public static bool IsNullEquivalent( this object value)
        {
            return value == null
                   || value is DBNull
                   || string.IsNullOrWhiteSpace(value.ToString());
        }
        public static bool IsEmpty( this DataRow row)
        {
            return row == null || row.ItemArray.All(i => i.IsNullEquivalent());
        }
    }

and i call it like this

DataRow[] row =getRowMethod();
if IsEmpty(row){"do some functionality"}

if i changed IsEmpty Signature by removing this keyword to below it works like this

   public static bool IsEmpty(  DataRow row)
            {
                return row == null || row.ItemArray.All(i => i.IsNullEquivalent());
            }
   if IsEmpty(row[0]){"do some functionality"}

i need to work with this extension to check any datarow and in future to check any datatable and can i use the below method to check null datatable

 public static bool IsEmptyDatatable (DataTable dt)
    {
        return dt == null || dt.Rows.Cast<DataRow>().Where(r=>r.ItemArray[0]!=null).All(i => i.IsNullEquivalent());
    }

Answer 1

finally i ended up with the bellow solution ,thank you people ...all what you suggested were helpful

 public static bool IsNullEquivalent( this object value)
        {
            return value == null
                   || value is DBNull
                   || string.IsNullOrWhiteSpace(value.ToString());
        }
        public static bool IsEmptyDataRow(this  DataRow row)
        {
            return row == null || row.ItemArray.All(i => i.IsNullEquivalent());
        }
        public static bool IsEmptyDatatable (this DataTable dt)
        {
            return dt == null || dt.Rows.Cast<DataRow>().All(i => i.IsEmptyDataRow());
        }