Keeps getting Class Not Found Exception for Postgres driver in eclipse plugin-Collection of common programming errors

I am developing a simple plugin for eclipse, which has one view connecting to Postgres. I have installed postgres which is running fine. I have a driver: postgresql-9.0-801.jdbc4.jar which was provided with the installation package.

Now I’m trying to connect to database using the code:

try {
    Class.forName("org.postgresql.Driver");
} catch (ClassNotFoundException cnfe) {
    cnfe.printStackTrace();
    return false;
}

Of course, I’ve added mentioned JAR to class path: right click on project > preferences > Java Build Path It is added to “Libraries”.

Still I get an error:

java.lang.ClassNotFoundException: org.postgresql.Driver

I have also checked the box in “Order and Export” tab.

What am I doing wrong?