There's a good chance the file is corrupt. As whomever sent it to you to verify it opens on their end.
That's it!? What if a person can't easily "just go back" Geese!
OMG, this IDML stuff is not working! There must be a better way!
@Diane – ask the creator of the IDML to export the IDML again. Before sending it, he/she should try to open it in the very version of InDesign it was exported from.
If this would work, the IDML should be zipped up and sent to you again.