Amazon doesn't accept Mobi because of "bug in header"

Hi,

We converted an Epub to a Mobi. I think it was Calibre version 0.9.5.
We used the option "both" for conversion.

Amazon does not accept the Mobi because "it might have a bug in the header"...

The statement from Amazon was like:
"The file was delivered as a Mobi, but has failed internally. Might you please check if it was produced with Calibre, because they have a bug in the header which might cause this problem."

"They create a time out in the publishing line..."

We already produced a lot of Mobis from Epubs with Calibre and we never had problems.

Any help appreciated.