sounds like your html is still calling sub build_select_field
change:
print &build_select_field ("Userid", "$rec{'Userid'}");
to
print &build_external_select_field ("Userid", "$rec{'Userid'}");
either remove the part of sub build_external_select_field that checks to be sure Userid (field or column) is defined in cfg or be sure it is defined in cfg in $external_select_field (or whatever the variable is; see my first reply)
change:
print &build_select_field ("Userid", "$rec{'Userid'}");
to
print &build_external_select_field ("Userid", "$rec{'Userid'}");
either remove the part of sub build_external_select_field that checks to be sure Userid (field or column) is defined in cfg or be sure it is defined in cfg in $external_select_field (or whatever the variable is; see my first reply)