Hi Vlad,
sorry but I don't have LV5 and I cannot check the name of the attribute node for you.
Check attached solution (is for lv 5.1) ... maybe it solves your problem.
Anyway, it would be helpful to give us some details about that graph (contained data) and why you cannot use input X values ... or post the critical part of your VI.
Let us know if you still have troubles
