Assistant won't show TOC when using collectionFile undex Linux

When using the "-collectionFile" option of assistant, the table of content is not displayed in the content dock:

assistant -collectionFile mycollection.qhc & => gives screenshot LinuxKo.png

When using the -register option without specifying any collection file evertything is ok.

assistant -register myhelp.qch
assistant &

gives screenshot LinuxOk.png

The content panel also have the Qt's docs (I could unregister them but that is not an option).

Under Windows (Xp, Qt4.7.0) using the same collection file it works fine.

attachment.zip contains all the files I use to reproduce the problem.

Any pointers appreciated.
Thanks.