load of image catalog

Hi,

I'm trying to update our v7r1 system to v7r3.
I've loaded all the DVDs to an Image Catalog (named V7R3).
I have a virtual optical device (VRTOPT) created and varied on.

But the last step (5) of the instructions (LODIMGCLG) fails with OPT1390.
Here's what that error description says:

/Message . . . . :   Error with virtual volume image. //
//Cause . . . . . :   The image object specified for the virtual optical volume //
//  is not a valid volume image or an error occurred when accessing the storage //
//  for the image object.  The virtual device used for the operation was VRTOPT.//
//Recovery  . . . :   Load an image that is a valid optical volume image and //
//  retry the operation. /

If I look at the entries in the Image Catalog (using option 12) shows the first entry
(I BASE 01) is now in Error status.  Before the LODIMGCLG attempt, it was Loaded.

I have used the IBM pre-upgrade verification tool for IBM i (on PC) and it verifies that
all the Required PTFS are permanently applied.  Including those that are supposed to
be needed for using an Image Catalog.

Does anyone know what's wrong here?
Are there further PTFs needed, or do I need to get with IBM?

Thanks in advance...

Thomas Garvey