Cannot find database driver: org.postgresql.Driver

Im trying to change a project a bit, by upgrading it with Liquibase. Its a Java EE project. So im using the liquibase-maven-plugin.

So far i have in my pom.xml:

  1.            
                    org.liquibase
                    liquibase-maven-plugin
                    2.0.5
                   
                        true
                        src/main/resources/liquibase.properties
                        src/main/resources/changelogs/changelog.xml
                   
                   
                       
                           
                           
                       
                   
               

which already includes a Driver:

  1.        
                postgresql
                postgresql
                9.1-901-1.jdbc4
           

the liquibase.properties file has the url, username, password, the changeLogFile-Path and the driver.
  1. #liquibase.properties
    driver: org.postgresql.Driver
The changelog.xml has a simple changeset which creates a table, just to test liquibase for the beginning.

But I dont come so far, because when I run the project with

  1. mvn liquibase:update

Im getting this error:

[ERROR] Failed to execute goal org.liquibase:liquibase-maven-plugin:2.0.5:update (default-cli) on project PROJECT: Error setting up or running Liquibase: java.lang.RuntimeException: Cannot find database driver: org.postgresql.Driver

I cant see the point… The driver has been already been used before with the project. So why cant liquibase find it?