oracle database connection from VS2010

Question

I am can successfully execute the following code on a particular web project on my local dev machine..

      string cStr = @"data source=xxxxxxx;user id=xxxxx;password=xxxx;persist security info=false";
      using (OracleConnection oc = new OracleConnection(cStr))
      {
          oc.Open();
          oc.Close();

      }

But if I try to execute it in any other project (web, console, Test), I get the following error.

OCIEnvCreate failed with return code -1 but error message text was not available.

I have googled and looked through this site and all the answers have not helped me so far. I really need help. So please do not down vote this question.

Here is my development machine setup...

Windows 7 Enterprise Service Pack 1 64 bit OS

Visual Studio 2010 Enterprise Service pack 1 IIS version 7.5

Oracle version 11.2.0

The working web application is targeting .net framework 4.

thanks

Answer 1

The problem is that there are several Oracle clients installed.

See this page of TechnoEncode