In your case then the Compay may be a small company and there may be not be any CS appointed.For small comp annual return is to be singed only by the director of the company, if CS is not appointed.
How it is possible?? Kindly check the form again. Whether the form was signed by PCS . If uploaded without PCS sign, kindly write to MCA helpdesk and inform your ROC in order to avoid difficulties in future.