Eclipse Juno : unassigned closeable value

I am wondering why I get this warning with the new eclipse Juno despite I think I correctly closed everything. Could you please tell me why I get this warning in the following piece of code?

public static boolean copyFile(String fileSource, String fileDestination)
{
    try
    {
        // Create channel on the source (the line below generates a warning unassigned closeable value) 
        FileChannel srcChannel = new FileInputStream(fileSource).getChannel(); 

        // Create channel on the destination (the line below generates a warning unassigned closeable value)
        FileChannel dstChannel = new FileOutputStream(fileDestination).getChannel();

        // Copy file contents from source to destination
        dstChannel.transferFrom(srcChannel, 0, srcChannel.size());

        // Close the channels
        srcChannel.close();
        dstChannel.close();

        return true;
    }
    catch (IOException e)
    {
        return false;
    } 
 }