This is what I am not getting right. So I tried both of the following and still retrieved nothing:
Like IIf(IsNull([Forms]![frmSearch]![BDR]),Like "*" Or [BDR] Is Null,"*" & [Forms]![frmSearch]![BDR] & "*")
Like IIf(IsNull([Forms]![frmSearch]![BDR]),Like "*" Or IsNull([BDR]),"*" &...