Navigation Attribute Problem

Hi,

in my info cube I have a master data infoobject. For this infoobject I activated a navigigation attribute and added it to the infocube. If I look at the data via "show data" every thing is all right. But if I add the navigation attribute to the displayed attributes suddenly some rows are not displayed any more. Does anyon has a hint for me why the add of the navigation attribute deletes rows of my result?

Best Regards

Michael