arguments for koji api "createEmptyBuild"

[Eric Zhong]

koji api "createEmptyBuild"  arguments problems:

[zhongwenjia@build ~]$ koji call createEmptyBuild nvidia 1 1.3 ""
Fault: <Fault 1: "<class 'pg.DatabaseError'>: error 'ERROR: 
operator does
not exist: text = integer\nLINE 2:     WHERE pkg_id=9168 AND version=1 AND
release='1.3'\n                                         ^\nHINT:  No
operator matches the given name and argument type(s). You might need to add
explicit type casts.\n' in 'SELECT id,state,task_id FROM build\n    WHERE
pkg_id=9168 AND version=1 AND release='1.3'\n    FOR UPDATE'">

[zhongwenjia@build ~]$ koji call createEmptyBuild nvidia 1.1 1.3 ""
Fault: <Fault 1: '<class \'pg.DatabaseError\'>: error \'ERROR: 
invalid
input syntax for integer: ""\nLINE 4:     VALUES
(18338,9169,\'1.1\',\'1.3\',\'\',\n
^\n\' in \'\n    INSERT INTO build
(id,pkg_id,version,release,epoch,state,\n
task_id,owner,completion_time)\n    VALUES
(18338,9169,\'1.1\',\'1.3\',\'\',\n           
1,NULL,1,\'NOW\')\n    \''>

[zhongwenjia@build ~]$ koji call createEmptyBuild nvidia 1.1 1.3 2
18339

[zhongwenjia@build ~]$ koji call createEmptyBuild nvidia 1.1 1.3
Fault: <Fault 1: "<type 'exceptions.TypeError'>: createEmptyBuild()
takes at
least 5 arguments (4 given)">

if version is a number , not string , how to do it ?
what is epoch argument ? Default is NULL. How to give a NULL value ?

koji-hub-1.3.2-1.fc13.noarch

Thanks