I followed KnowRob basics.

I run:

sam@sam:~$  rosrun rosprolog rosprolog mod_vis
% library(swi_hooks) compiled into pce_swi_hooks 0.01 sec, 3,856 bytes
%     library(error) compiled into error 0.00 sec, 18,280 bytes
%    library(lists) compiled into lists 0.00 sec, 45,000 bytes
%   library(shlib) compiled into shlib 0.00 sec, 66,216 bytes
%   library(option) compiled into swi_option 0.00 sec, 15,576 bytes
%  library(process) compiled into process 0.00 sec, 99,464 bytes
% /opt/ros/groovy/stacks/knowrob/rosprolog/prolog/init.pl compiled 0.00 sec, 107,288 bytes
%    library(jpl) compiled into jpl 0.01 sec, 306,568 bytes
%        library(sgml) compiled into sgml 0.00 sec, 43,008 bytes
%          library(quintus) compiled into quintus 0.00 sec, 21,208 bytes
%         rewrite compiled into rewrite 0.00 sec, 34,568 bytes
%         library(uri) compiled into uri 0.00 sec, 14,648 bytes
%         library(record) compiled into record 0.00 sec, 35,128 bytes
%        rdf_parser compiled into rdf_parser 0.01 sec, 153,424 bytes
%         library(gensym) compiled into gensym 0.00 sec, 4,616 bytes
%        rdf_triple compiled into rdf_triple 0.00 sec, 38,688 bytes
%       library(rdf) compiled into rdf 0.02 sec, 269,384 bytes
%        library(debug) compiled into prolog_debug 0.00 sec, 22,112 bytes
%        library(assoc) compiled into assoc 0.00 sec, 35,904 bytes
%       library(sgml_write) compiled into sgml_write 0.00 sec, 121,240 bytes
%       library(nb_set) compiled into nb_set 0.00 sec, 6,200 bytes
%        library(utf8) compiled into utf8 0.00 sec, 13,824 bytes
%       library(url) compiled into url 0.01 sec, 114,840 bytes
%       rdf_cache compiled into rdf_cache 0.00 sec, 16,184 bytes
%      library(semweb/rdf_db) compiled into rdf_db 0.04 sec, 699,784 bytes
%     comp_similarity compiled into comp_similarity 0.05 sec, 727,888 bytes
%    /opt/ros/groovy/stacks/knowrob/ias_prolog_addons/prolog/init.pl compiled 0.05 sec, 728,880 bytes
%     library(broadcast) compiled into broadcast 0.00 sec, 7,520 bytes
%    library(semweb/rdf_edit) compiled into rdf_edit 0.00 sec, 86,640 bytes
%    library(semweb/rdfs) compiled into rdfs 0.00 sec, 25,928 bytes
%    library(semweb/owl) compiled into t20_owl 0.00 sec, 67,952 bytes
%      library(socket) compiled into socket 0.00 sec, 12,488 bytes
%      library(base64) compiled into base64 0.00 sec, 17,704 bytes
%     library(http/http_open.pl) compiled into http_open 0.02 sec, 104,200 bytes
%    library(thea/owl_parser) compiled into owl_parser 0.02 sec, 186,216 bytes
%     library(odbc) compiled into odbc 0.00 sec, 37,960 bytes
%    library(semweb/rdfs_computable) compiled into rdfs_computable 0.00 sec, 104,216 bytes
%   /opt/ros/groovy/stacks/knowrob/semweb/prolog/init.pl compiled 0.10 sec, 1,569,480 bytes
%       library(tf_prolog) compiled into tf_prolog 0.00 sec, 22,176 bytes
%      /opt/ros/groovy/stacks/knowrob/tf_prolog/prolog/init.pl compiled 0.00 sec, 25,392 bytes
%        library(crypt) compiled into crypt 0.00 sec, 3,312 bytes
%       library(knowrob_owl) compiled into knowrob_owl 0.00 sec, 28,608 bytes
%       library(knowrob_perception) compiled into knowrob_perception 0.00 sec, 24,416 bytes
% Parsed "knowrob_objects.owl" in 0.01 sec; 202 triples
%      library(knowrob_objects) compiled into knowrob_objects 0.02 sec, 206,240 bytes
%       library(owl_export) compiled into owl_export 0.01 sec, 22,048 bytes
%      library(knowrob_coordinates) compiled into knowrob_coordinates 0.01 sec, 44,232 bytes
%     /opt/ros/groovy/stacks/knowrob/knowrob_objects/prolog/init.pl compiled 0.03 sec, 296,152 bytes
%     library(knowrob_actions) compiled into knowrob_actions 0.00 sec, 12,832 bytes
%    /opt/ros/groovy/stacks/knowrob/knowrob_actions/prolog/init.pl compiled 0.04 sec, 328,104 bytes
%     library(util) compiled into util 0.00 sec, 27,456 bytes
%    library(classifiers) compiled into classifiers 0.00 sec, 51,344 bytes
%    library(jython) compiled into jython 0.01 sec, 24,136 bytes
% Parsed "owl.owl" in 0.00 sec; 169 triples
% Parsed "knowrob.owl" in 0.07 sec; 3,975 triples
%   /opt/ros/groovy/stacks/knowrob/ias_knowledge_base/prolog/init.pl compiled 0.13 sec, 691,600 bytes
%  /opt/ros/groovy/stacks/knowrob/knowrob_common/prolog/init.pl compiled 0.24 sec, 2,284,216 bytes
%   library(knowrob_cad_parser) compiled into knowrob_cad_parser 0.00 sec, 13,648 bytes
%  /opt/ros/groovy/stacks/knowrob/knowrob_cad_parser/prolog/init.pl compiled 0.00 sec, 16,872 bytes
%  library(mod_vis) compiled into mod_vis 0.01 sec, 37,544 bytes
% /opt/ros/groovy/stacks/knowrob/mod_vis/prolog/init.pl compiled 0.25 sec, 2,372,552 bytes
?- owl_subclass_of(A, knowrob:'FoodOrDrink').
A = 'http://ias.cs.tum.edu/kb/knowrob.owl#FoodOrDrink' ;
false.

?- 

Why even I use ';' to show all the answers, I can't get any one?

How to solve it?

Thank you~