Why "Delta Update" radio button fails to show up on BW 3.5 in an InfoPackag

Our BASIS has just installed a BW 3.5, after we've installed some business contents, I check the InfoPackage 0BPARTNER_TEXT_DELTA_IPM_CRM under the InfoSource called "BP Texts" and also under the BW source system, find that under Update tab of this InfoPackage, the radio button "Delta Update" fails to show up on BW 3.5, but it does exist on BW 3.1 that's our old system designed by previous coworkers. We have no idea on how to make this radio button "Delta Update" show up on BW 3.5.

Anyone's idea is greatly appreciated!