Apologies if this is a really simple question but I haven't been using VBA for all that long.

I am trying to work out if I can activate an open workbook without referencing the whole name?

Essentially every month 100 or so files will open automatically, but each month the name changes slightly as the file name references the month.
Therefore when I select a file I just want to use the 'constant' terms in the name to find the file.

I have tried the below, using the * tool but it tells me the subscript is out of range:

i.e

Application.Workbooks("MLSS*.xls").activate

Is there something fundamental I'm missing?

Thanks for any help

Joe