I want to change all the cost expressions to Python for my network dataset. They are currently in VB. Python is grayed out for some reason. I tried to create a new attribute and set it, but Python is still grayed out. I am trying to avoid starting from scratch, but am thinking that because other attributes are in VB, it might think I am trying to have a mix of VB and python which may not be allowed, therefore I would have to delete all attributes using VB costs and start from scratch.