I have this problem in two directions, read and write. It's obviously
an access (small "a") problem.The problem workbook  is hidden. It comes
about this way.

WB1 is the workbook I already have open. No problem with it. In the
declarations of this workbook I set  WB1 and WB2 as object  variables (I
think my nomenclature is correct -- I use "Set WB1 = fullpathname for
first WB" and have another statement set statement for the second
workbook, which I do not open.)Therefore WB2 never "opens"; it shows
as a hidden  file in Excel's Window-->Unhide dropdown.

The main routine  in WB1 starts a loop for analyzing data that are
organized by day. WB2 contains multiple columns  of daily data. At the
beginning of every WB1 loop I go out to WB2, copy  the next column, and
paste it into a column  in WB1 for processing. This is the problem. I
cannot copy any data from WB2, even though I can use a subroutine that
goes into WB2 and counts the number  of filled columns.

I have another routine in another workbook that is trying to paste
data into the same WB2 workbook. It doesn't work  either.

So, I can do something with WB2, but cannot copy from or paste  to it.
Have searched through all my books for a solution, and nothing I've
found works. Is it possible?

I plan to try another tact, whereby I'll open WB2 directly, load a
whole sheet  into an array and then loop through the array columns, but
would really like to know if there is a solution for the first way.