InfoPackage does not display selection field...

We are trying to select data for extraction based on an R/3 field that is decimal(21,7). It is a timestamp field and not really a key figure. We want to be able to select data based on this field in InfoPackage.

The field is in the DataSource and the 'Selection' box is checked. However, the field doesn't even show up in the InfoPackage selection list. We are forced to perform full extracts due to the absence of this field in the InfoPackage selection list.

How do we overcome this problem?