After I had successfully connected to Oracle 10 XE, I had another problem...
when using a zquery or a ztable in certain cases the program returned the oci error 01406 
, I was shure that my database was ok and after a lot of temptatives and tests I found that the guilty of all that problem was the clientcodepage.... 
, I have not had to use this parameter in connections to Firebird or to Postgres, and that was the problem I didn't realize that that property was there 
, so:If you have such a problem using zeos with Oracle (at least with 10 XE) you have to:
be shure that the property AutoEncodeStrings is set to TRUE and
select the proper code page in the dropdownbox of the Clientcodepage that matches your system code page, then:
enjoy this components !!!
makes you wise !!!