What's the problem?

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using InfinityScript;

namespace zm
{
   public class ZombieMod : BaseScript
   {
             entity.SpawnedPlayer += new Action(() =>
               {
                   if (entity.GetField("sessionteam") == "axis")
                   {
                     entity.Call("visionsetnakedforplayer", "ac130_thermal_mp", 0);
                     entity.Call("ThermalVisionFOFOverlayOn");
                    }
               });
    }
}

Well you don't have a constructor in your class....

I suggest you watch some YouTube videos or something about C# to learn the basics

maybe if you use this?

public ZombieMod()
           : base()

Thanks, it works!

source:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using InfinityScript;

namespace zm
{
   public class ZombieMod : BaseScript
   {
       public ZombieMod()
           : base()
       {
           PlayerConnected += new Action(entity =>
             {
                 entity.SpawnedPlayer += new Action(() =>
                      {
                          if (entity.GetField("sessionstate") != "axis")
                          {
                              entity.Call("visionsetnakedforplayer", "ac130_thermal_mp", 0);
                              entity.Call("ThermalVisionFOFOverlayOn");
                          }
                      });
             });
    }
   }
}

And the point of this is? All I can tell is that it's an initial section of a zombie mod. i.e. the FOFOverlay and the ac130_thermal as well as the name...