The GIB can't notice penalty situations and always bid after a double even on 4th level. Have a look at this hand: [hv=https://www.bridgebase.com/tools/handviewer.html?lin=st||pn|~~v3fakebot,~~v3fakebot,fimre,~~v3fakebot|md|4ST64HT982DA2CAKQ6,SQHAK43DKJ9643C53,SAK532HQDT5C98742,SJ987HJ765DQ87CJT|sv|b|rh||ah|Board%2010|mb|P|mb|1C|an|Minor%20suit%20opening%20--%203+%20!C;%2011-21%20HCP;%2012-22%20total%20points|mb|1D|an|One-level%20overcall%20--%205+%20!D;%208-17%20HCP;%209-19%20total%20points|mb|1S|an|Free%20bid%20--%204+%20!S;%206+%20total%20points;%20forcing|mb|P|mb|1N|an|3-5%20!C;%202-4%20!D;%202-4%20!H;%202-3%20!S;%2012-14%20HCP|mb|2D|an|6+%20!D;%2017-%20HCP;%2012-19%20total%20points|mb|3C|an|4+%20!C;%204+%20!S;%209+%20total%20points|mb|P|mb|P|mb|3H|an|6+%20!D;%204+%20!H;%2017-%20HCP;%2018-19%20total%20points|mb|P|mb|4D|an|2+%20!D;%208-%20total%20points|mb|D|an|3-5%20!C;%202-4%20!D;%202-4%20!H;%202-3%20!S;%2014%20HCP;%2015%20total%20points|mb|P|mb|4S|an|4+%20!C;%206+%20!S;%209+%20HCP;%2010-17%20total%20points|mb|P|mb|P|mb|P|pc|D7|pc|DA|pc|D4|pc|D5|pc|S4|pc|SQ|pc|SA|pc|S8|pc|SK|pc|S9|pc|S6|pc|H4|pc|C2|pc|CJ|pc|CA|pc|C3|pc|CK|pc|C5|pc|C4|pc|CT|pc|CQ|pc|D6|pc|C7|pc|S7|pc|SJ|pc|ST|pc|D9|pc|S2|pc|H7|pc|H2|pc|HK|pc|HQ|pc|DK|pc|DT|pc|D8|pc|D2|pc|DJ|pc|S3|pc|DQ|pc|C6|mc|9|]400|300|[/hv] 4♦ doubled would be +100, but 4♠ couldn't be made and struck a bottom. Why isn't t/o double limited upto 3♠ as common?