HSMC GPIO Daughter card open-drain error

Using Quartus 14.1 I created a design for my DE2-115 dev board. I have the IO expansion card used in my design. Upon compilation i get the following error for all HSMC pins used:

Error (169008): Can't turn on open-drain option for differential I/O pin HSMC_TX_D_P[16]

I have no idea which settings I need to change in order to achieve a successful compilation. Could you help me on my way?