[OOT] timestamp / time ('now') in postgresql 7.2?

hi

i'm have installed latest version of postgresql which is 7.2
why i can not use timestamp('now') or time('now') ?
it said : ERROR:    parser: parse error at or near "'"

can anyone explain why?
i'm try in 7.1.x. it's works well
did i miss something when installation? is it in new version need somekind
of "plug-in"?

ps: date('now') is work fine

thx in advance