I get invalid login,password or locked out when I try to run the ant migration tool. I have changed password and security token and still have the same problem. This used to work. Did something change?

Below is my buld.xml (with user name and password changed) followed by build.properties. Any idea how to fix or debug?
Thanks
Bob

Build.xml
<project name="Sample usage of Salesforce Ant tasks" default="test" basedir="." xmlns:sf="antlib:com.salesforce">

    <property file="build.properties"/>
    <property environment="env"/>

    <!-- Setting default value for username, password and session id properties to empty string
         so unset values are treated as empty. Without this, ant expressions such as ${sf.username}
         will be treated literally.
    -->
    <condition property="sf.username" value=""> <not> <isset property="sf.username"/> </not> </condition>
    <condition property="sf.password" value=""> <not> <isset property="sf.password"/> </not> </condition>
    <condition property="sf.sessionId" value=""> <not> <isset property="sf.sessionId"/> </not> </condition>

    <taskdef resource="com/salesforce/antlib.xml" uri="antlib:com.salesforce">
        <classpath>
            <pathelement location="../ant-salesforce.jar" />            
        </classpath>
    </taskdef>

    <target name="getFalcon">
      <mkdir dir="Falcon"/>
      <sf:retrieve
          username="${sf.username}"
          password="${sf.password}"
          serverurl = "login.salesforce.com"
          retrieveTarget="Falcon"
          packageNames="Falcon1"/>
    </target>

Build.properties
# build.properties
#

# Specify the login credentials for the desired Salesforce organization
sf.username = username
sf.password = password
#sf.sessionId = <Insert your Salesforce session id here.  Use this or username/password above.  Cannot use both>
#sf.pkgName = <Insert comma separated package names to be retrieved>
#sf.zipFile = <Insert path of the zipfile to be retrieved>
#sf.metadataType = <Insert metadata type name for which listMetadata or bulkRetrieve operations are to be performed>

# Use 'https://login.salesforce.com' for production or developer edition (the default if not specified).
# Use 'https://test.salesforce.com for sandbox.
sf.serverurl = https://login.salesforce.com

sf.maxPoll = 20
# If your network requires an HTTP proxy, see http://ant.apache.org/manual/proxy.html for configuration.
#