Image size scaling proportional in reflowable ePub 2.01

I am struggeling with an ePub book. It´s a reflowable book set in ePub 2.01, exported from latest version of Indesign CC.

My problem is that the images looks fine in iBooks but in ADE the images are stretch in height. Why? How to avoid? Please help!

Insert settings of export here:

First three are object style settings. Last three are epub export settings.

/Desperately Petra