LM3401 Hysteretic PFET Controller Dimming problem

I am using the LM3401 for a lighting project and I've had the board up and running for a while. Before now I have had the DIM pin tied to my Vin until i began to work on my MCU to power the PWM signal. Now that i am at that phase i have tried to input a PWM signal to DIM pin to dim the LED but no dimming occurs. I began troubleshooting and have found out that the LED lights up regardless of any signal tied to the DIM PIN even if i just have it disconnected and floating the circuit is still operating normally. According to the data sheet if the DIM pin is not receiving a voltage signal higher than 2V HG pin should go low and cut off the mosfet. I need some guidance as to what could be going wrong and why the circuit isn't operating as it should...