Recently I find weird bug in LabVIEW .
if you try to save a cluster with at least two string side it with using flatten to string vi for saving as a text file, it is ok and you can recall it with unflatten from string vi later, unless you fill at least one of the strings with 13 characters inside it, in this case, unflatten from string not work well and you could not recall data back?!!
that is weird