@AlexRPA
If you just need to sum a column, I would suggest using the syntax like this:
tblaccount.AsEnumerable.Sum(Function(x) Convert.ToDouble(x("AVAIL_BALANCE").ToString.Trim) ).ToString
You can filter to only certain columns also using .Where, like this:
tblaccount.AsEnumerable.Where(Function(x) x("column").ToString.Trim.Equals("123456")).Sum(Function(x) Convert.ToDouble(x("AVAIL_BALANCE").ToString.Trim) ).ToString
I hope this helps.
Regards.