need to open a port

i need to open 8484 port for primavera, i have three servers here, 1 for domain 2nd for isa n 3rd one for primavera… isa n primavera is under in doamian server… domain n primvras server gtin intrnt connction thru isa…i open this port in pramavera server n isa also n i tried to open the primavera web aplication for admin config,but i get an error msg lik the page cannt be desplayed… how i can solve this problm..plz help me…. then the os r in domain:windows 2008 server LM enterpris edition,
isa: windows 2003 server
primavera: windows 2008 server