Ok, a little modification is in order:

You only have to code OPEN = DEFER once because it applies to all input tables. So it doesn't have to be part of the loop.

Secondly, when the tables don't contain the same variables only the variables from the first table will be saved. Any extra variables will be ignored.

So it's wise to create a table that contains all the variables you want but no observations. Put that table on the set statement as the first table to load.