NCOCI8 try to load it from selected (active) Oracle home. Oracle home is active, if they ORACLE_HOME\Bin directory is contained in PATH environment variable. And it mast be first from other Oracle home BIN directories. Now goes the algorythm, how NCOCI8 try to load OCI.DLL.

NCOCI8 walks through all Oracle home, that are recorded in registry in next order:
HKLM\Software\Oracle
HKLM\Software\Oracle\Home0
.....
HKLM\Software\Oracle\HomeN
And try to get value of ORACLE_HOME of each home. Then appends BIN to that path, and search it in environment variable PATH. The Oracle home and it BIN directory, that is first in PATH will be used by NCOCI8. In that BIN directory NCOCI8 try to load OCI.DLL or value of ORAOCI.

So, if you get this error message, it seems, that you did not have valid BIN directory in PATH or some problems with registry structure. Moreover, there may be bugs from Oracle. NCOCI8 in that part is too many times tested :) So, if my hint cant help you, please send to me next information, and i will try to solve issue:

• server & client versions;
• NCOCI8 version;
• export of HKLM\Software\Oracle;
• value of PATH variable.