Run-time error '3706'. Provider cannot be found. It may not be properly installed.

[cboshdave]

I am getting the following error when I try to connect to Oracle from Excel 2007 vba. Error: "Run-time error '3706'. Provider cannot be found. It may not be properly installed."
I am using the following code:

Dim conn As New adodb.Connection
Set conn = New adodb.Connection
connStr = "Provider=OraOLEDB.Oracle;Data Source=SchemaName;User Id=UserName;Password=PW;"
conn.Open connStr

I do not have the Oracle client installed on this machine. I am hoping I can using MS native drivers rather than installing Oracle on every machine.

I can't figure out why I am getting this error? Am I missing references?