Hi ,
If you are able to accees the application manually with all the 5 Vusers ,then u can these 2 option into Vugen for running all the 5Vusers(ID'S) sucessfully.
Goto Runtime Settings....>Click Browser Emulation
1) Enable "Simulate a new user on each iteartion"
2) Clear cache on each iteration
Thanks,
KMR-Hexa