ant - 'C:\Program' is not recognized error -

i set ant_home=c:\program files\ant-1.8.0 try build local host weblogic.
but, gives me following error:

c:\program' not recognized internal or external command.

i tried putting quotes when defining variable: "ant_home=c:\program files\ant-1.8.0". not working either, it shows following error message:

files\ant-1.8.0""=="" unexpected @ time.

i have been stuck here past few weeks. iv'e googled many times still cant resolve problem.

edited:

dir c:\pro /x

didn't show progra~1 , progra~2

set "var=content" practice avoid having unintended trailing spaces, error occures when using value. there need qoutes (that not part of variable content above syntax):

set "folder=c:\program files" dir %folder% dir "%folder%" 

the first dir give "file not found", because tries show contents of c:\program (which doesn't exist) plus contents of files (which doesn't exist). second dir show contents of "c:\program files"