You have made it far too complicated
begin
if ([F001]/[F002])*100 >= 90 and ([F001]/[F002])*100 < 95 then
Result := [F001] * 0.01
else if ([F001])/[F002])*100 >= 95 and ([F001])/[F002])*100 < 100 then
Result := [F001] * 0.01125
else if ([F001]/[F002])*100 >= 100 and ([F001]/[F002])*100 < 105 then
Result := [F001] * 0.0125
else if ([F001]/[F002])*100 >= 105 then
Result := [F001] * 0.015
else
Result := 0;
end;
Start from simple than slowly increase complexity
Mike