ip university program error

Good evening to all,

I downloaded the IP core univeristy program at the following site of otherness: http://www.altera.com/education/univ/materials/ip-cores/unv-ip-cores.html; these I need to get on the SOPC builder ps2 component and VGA. But every time I add items to this package gives me the following error: Warning: altera_up_avalon_ps2: set_interface_property: Interface Does Not Have a external_interface parameter associatedClock ..

What does it mean? How do I fix this?

Thanks