It sounds like you may just be grabbing the VMDK descriptor file, and not the associated "-flat" file from the datastore. The -flat file, as you know, is where the VM guest's data actually lives.
What is the command that you are issuing to grab the VMDK file(s)?
And, to help illustrate the fact that there are "pairs" of VMDK files (a regular descriptor file and the associated -flat file) in the VM folder, you can call something like:
Get-ChildItem vmstores:\vcenter.dom.com@443\myDatacenter\myDStore02\myVM0\*vmdk | ft -a Name,ItemType,Length
From that you should see at least two VMDK files (two per virtual disk on the VM). That help?
BTW: those datastore browser paths provided by the VimDatastore PSProvider are case sensitive, if you did not already see.