I am looking for the VBA equivalent for the following function:

=isnumber(value(mid("Export20090224.xls",7,8)))

What I am trying to do is make sure that when the user saved the filename
that they entered the date properly as in 20090224 rather than 2009224. Maybe
this is a weak approach as I am just testing for the length more than
enything else. Can I get the date from the 'saved date' stamp pehaps?

If there is an even better way of doing this, then that would be great.

Thanks