Form I130 Submitted - no receipt notice

[P412]

Hello All,

We submitted I130 & I485 for my parents at the same time, we received I797 for one application while no response for the other one, it's been a month. Has anyone else had similar situation. If yes, how long does it usually take? We did send an email to lockbox but no response from them.
Would appreciate if someone could suggest or give some inputs. Thanks in advance.

- Pia