why i cannot use php imap functions in my ubuntu and windows?

i need imap function to do a login test, so i can perform a single sign on/single log in like this stackoverflow do with email accounts. when 开发者_开发技巧i try the imap_open functions in windows, i got Fatal error:undefined function, but in ubuntu, i don't get anything. any codes bellow the function is not working, but there is no error. can anyone help me?

in ubuntu, i've installed php5-imap, in windows. i've removed the ";" in front of the extension=imap.dll, i guess thats the thing..

thanks before,,

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I've found my mistakes.

I restarted my apache in a wrong way after installing PHP IMAP in ubuntu and removing the ';' in Windows.

thanks for reading.