Virsh Console Can't Access to rhel VM (a pty console, instead of serial console)

Question

1. the pty console:

<console type='pty'>
    <target type='virtio' />
    <alias name='console1'/>
</console>

2. no output when I exec the command virsh ttyconsole vm_name
3. the log (/var/log/libvirt/qemu/vm_name.log) :

char device redirected to /dev/pts/2 (label charconsole1)

4. when l exec virsh console vm_name console1 , the command is stuck. Only output:

Connected to domain vm_name
Escape character is ^] (Ctrl + ]) (i had pressed enter button)

5. I had tried some methods(RHEL6 virsh console domain),like editing /boot/grub/menu.lst and /etc/inittab. But it can't solve the problem.