XFEM modelling in ABAQUS

Hi

I am modelling the crack propagation in metals. I can do all the modelling but only adding the enrichment function in ABAQUS is an issue. I have defined the initial crack(for the CT speciemn), which starts at the node, but when I submitt the job it does not separate at that node. I think it because I did not define the enrichment functions.

I would  like to know how to add enrichment function in abaqus when modelling the crack propagation. Any suggestion would be appreciated.

Thanks in advance

Oscar