Linked server to Oracle

Hello,

I have a MS SQL Server 2008 R2 running on Windows 2008 R2 Server.

I have installed Oracle Client 12.1 software. TEsT connect to remote Oracle DB works.

But I have problems adding a linked server to MSSQL.

I try:

EXEC sp_addlinkedserver 
  'OracleLinkedServer', 'ORCL', 
  'ORAOLEDB.ORACLE', 'Oraclelinkedserver' ;

EXEC sp_addlinkedsrvlogin  
  'OracleLinkedServer', false, 
  NULL, 'username',
  'password' ;

When I want to browse the linked server tables this is the error I get:

OraOLEDBpus12.dll. The specified module could not be found.

What am I doing wrong?

Thx

M