[SOLVED] Index was out of range on an ADOQuery

Index was out of range on an ADOQuery - Very Random

I am getting Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index randomly emailed through to me on my website. I cannot reproduce this error either by force or general testing and it is somewhat confusing.

From what I can see in the stack trace, it happens randomly when opening a dataset and trying to get a value. The stack trace showed I got the error when calling this function:

function TDB.FGetLastInsertID: Integer;
const
  selSQL = 'select scope_identity() as LastID';
var
  selCursor: TDataSet;
begin
  selCursor := Cursor(selSQL); //Returns a DataSet from a TADOQuery
  try
     Result := selCursor.FieldByName('LASTID').AsInteger;
  finally
     selCursor.Close;
     selCursor.Free;
  end;
end;

As I said, I cannot get this to reproduce the error and it seems to happen randomly on any query I run. I have tried closing the connection, setting it to inactive ect to reproduce the error but cannot.

Has anyone got any ideas?

EDIT: It seems its the close causing issues after examining the stack trace more closely:

Stack Trace: at 
System.Collections.ArrayList.get_Item(Int32 index) at 
Borland.Vcl.TList.Delete(Int32 Index) at Borland.Vcl.TList.Remove(Object Item) at 
Borland.Vcl.TDBBufferList.FreeHGlobal(IntPtr Ptr) at 
Borland.Vcl.TCustomADODataSet.FreeRecordBuffer(IntPtr& Buffer) at 
Borland.Vcl.TDataSet.SetBufListSize(Int32 Value) at  
Borland.Vcl.TDataSet.CloseCursor() at  
Borland.Vcl.TDataSet.SetActive(Boolean Value) at Borland.Vcl.TDataSet.Close()

EDIT2: I have put a check in the code to make sure the selCursor.Active before selCursor.Close. The stack trace suggests there is nothing to close.

Solution

Very odd and I still don't know why but it seems that randomly the Cursor is already closed. It seems that adding:

if (selCursor.Active) then
    selCursor.Close;

has sorted the issue ...

Thanks for the answers and time spent trying to help.