limitation of custom script tag in quester

trying to wait on my partymembers in a questing profile. this works as runcode:

        int readyMembers = 0;
        var totalMembers = wManager.Wow.Helpers.Party.GetParty().Count();
        while (readyMembers != totalMembers)
        {
            readyMembers = wManager.Wow.Helpers.Party.GetParty().Where(u => u.GetDistance <= 5).Count();
            System.Threading.Thread.Sleep(3000);
        }

but the second i run the folowwing in the script tag
 

wManager.Wow.Helpers.Party.GetParty().Where(u => u.GetDistance <= 5).Count();

i get the error:
 

Quester.Bot > Pulse(): System.NullReferenceException: Object reference not set to an instance of an object.
   at Quester.Bot.Bot.Pulse(Boolean loadSettingsProfile, String profile)

same happens to any for and foreach loops, everything else is working fine in the script tag. anyone know what the exact error here?