Gratuity for managing director / director

I resigned from a Pvt Ltd company as a MD after +6 years of service. I was drawing a monthly salary along with other employees with the normal TDS and PF deductions. Recently, I also got my PF dues. I wasn't given any formal employment offer letter, except the one filed with ROC towards my monthly compensation. The company is now refuting the payment of Gratuity saying that as a Director / MD, I am not entitled to Gratuity. The Articles is silent on this. Is this view correct? Should I consider legal action or write to the Controlling Authority (Payment of Gratuity Act). Thanks