Modelsim Error: BFM model not available

I am trying my hand on reference design of PCI Express with the help of "ip compiler for pci express (https://www.altera.com/literature/ug/ug_pci_express.pdf)" document. While trying to simulate design using Modelsim got stuck with error "BFM model is not available". How I can rectify this problem ?

Attaching snapshots of error and part of code where execution is stopping.