oci_connect returns warning if provided with the 4th param(charset)

Hi all,

I used the following in my code
....
oci_connect('$user','$pass',$connectionString,'UTF8');
....

and got the following warning:

Warning: oci_connect() [function.oci-connect]: Invalid character set name: 
UTF8


I tried many times and found it could only work when I removed 'UTF8' or 
replaced it with 'US7ASCII'. It didn't work even I used 'WE8ISO8859P1'. But 
I had to use 'UTF8' in order to support multiple bytes.  I had tried setting 
NLS_LANG to AMERICAN_AMERICA.UTF8 in envvars instead of using the 4th 
parameter in oci_connect, but it didn't work. Using putenv to set NLS_LANG 
didn't work either.


Does anyone encounter this weird issue before? The php version I'm using is 
5.2.1.



Thanks for any help.