Toolbar in transaction COOIS: Why am I unable to add a pushbutton in the toolbar in transaction COOIS?
Transaction COOIS is one of the rare cases in the SAP system where no standard toolbar is used. The toolbar looks like the normal toolbar, but in fact it is integrated into the grid control.

Workaround:

Use pos X[CUSTOM] (1,0)
Pushbutton (0,0)  ....