Probably your software is only un-gziping but not untarring the file. The ".tar.gz" extension means a "tarball of files compressed using gzip compression". Try adding ".tar" back onto the resulting file and see if that lets your software un-tar it.
And that fixed it!! I changed the date-6.x-2.4 file to add .tar to the end, then opened that, and it worked!!! I've never had one need that done before and so didn't know what to do!! I hope I can remember for next time!!
THANKS!
Tina