I was searching the cause of this error.

Here is as reproduce it.

1. Put a tib_connection, tib_navigationbar(ib_Navigationbar1), a
tib_cursor(ib_Cursor1) and a tib_datasource(ib_Datasource1).

2. Make IB_DataSource1.Dataset:=ib_Cursor1

3. Make ib_Navigationbar1.Datasource:=IB_DataSource1

4. Put some select statement in tib_cursor

5. Call open or first in tib_cursor and following click on next arrow of the
ib_Navigationbar1.

6. Then you get the error.

This error is related to ValidateRows rotine being called in
IB_Navigation.pas.

To fix it, I have to comment this line in IBA_Dataset.imp:

function TIB_Dataset.ValidateRows( Start, Finish: longint ): boolean;
begin
// Abstract at this level.
raise EIB_DatasetError.Create( 'Not implemented' );
end;

If I comment:
--> // raise EIB_DatasetError.Create( 'Not implemented' );

The error disappears.

When using IB_WISQL compiled with IBO 3.6.D.d or 3.6.D.d.e and simulation
this same actions there, occur again this error and I have to do
CTRL_ALT_DEL to kill IB_WISQL .

Luiz.