UNet Networking problem

I am making a 2D topdown multiplayer game with the new UNet networking.

Here is the part that has errors

 void Update () {
     if (Input.GetMouseButtonDown(0)) {
         CmdShoot (name, GetComponent<NetworkIdentity ().connectionToServer);
     }
 }

 [Command]
 void CmdShoot (string ownerName, NetworkConnection connection) {
     GameObject b = (GameObject)Instantiate (bullet, bulletSpawn.position, bulletSpawn.rotation);
 
     Destroy (b, 5f);
 
     b.GetComponent<SpriteRenderer>().sprite = weapons[selectedWeapon].bullet;
     bulletScript bs = b.GetComponent<bulletScript>();
     bs.bulletSpeed = weapons [selectedWeapon].speed;
     bs.damage = weapons [selectedWeapon].damage;
     bs.ownerName = ownerName;
     b.GetComponent<NetworkIdentity> ().AssignClientAuthority (connection);
     Debug.Log (b.GetComponent<NetworkIdentity> ().clientAuthorityOwner);
 
     NetworkServer.Spawn(b);
     RpcSpawnBulletClient (ownerName);
 }

 [ClientRpc]
 void RpcSpawnBulletClient (string ownerName) {
     GameObject b = (GameObject)Instantiate (bullet, bulletSpawn.position, bulletSpawn.rotation);

     Destroy (b, 5f);

     b.GetComponent<SpriteRenderer>().sprite = weapons[selectedWeapon].bullet;
     bulletScript bs = b.GetComponent<bulletScript>();
     bs.bulletSpeed = weapons [selectedWeapon].speed;
     bs.damage = weapons [selectedWeapon].damage;
     bs.ownerName = ownerName;
 }

and there are three errors:

1.  UNetWeaver error: Exception :System.ArgumentException: Member 'System.Int32 UnityEngine.Networking.NetworkConnection::hostId' is declared in another module and needs to be imported
      at Mono.Cecil.MetadataBuilder.LookupToken (IMetadataTokenProvider provider) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.Cil.CodeWriter.WriteOperand (Mono.Cecil.Cil.Instruction instruction) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.Cil.CodeWriter.WriteInstructions () [0x00000] in <filename unknown>:0 
      at Mono.Cecil.Cil.CodeWriter.WriteResolvedMethodBody (Mono.Cecil.MethodDefinition method) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.Cil.CodeWriter.WriteMethodBody (Mono.Cecil.MethodDefinition method) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.MetadataBuilder.AddMethod (Mono.Cecil.MethodDefinition method) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.MetadataBuilder.AddMethods (Mono.Cecil.TypeDefinition type) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.MetadataBuilder.AddType (Mono.Cecil.TypeDefinition type) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.MetadataBuilder.AddTypeDefs () [0x00000] in <filename unknown>:0 
      at Mono.Cecil.MetadataBuilder.BuildTypes () [0x00000] in <filename unknown>:0 
      at Mono.Cecil.MetadataBuilder.BuildModule () [0x00000] in <filename unknown>:0 
      at Mono.Cecil.MetadataBuilder.BuildMetadata () [0x00000] in <filename unknown>:0 
      at Mono.Cecil.ModuleWriter.<BuildMetadata>b__0 (Mono.Cecil.MetadataBuilder builder, Mono.Cecil.MetadataReader _) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.ModuleDefinition.Read[MetadataBuilder,MetadataBuilder] (Mono.Cecil.MetadataBuilder item, System.Func`3 read) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.ModuleWriter.BuildMetadata (Mono.Cecil.ModuleDefinition module, Mono.Cecil.MetadataBuilder metadata) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.ModuleWriter.WriteModuleTo (Mono.Cecil.ModuleDefinition module, System.IO.Stream stream, Mono.Cecil.WriterParameters parameters) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.ModuleDefinition.Write (System.IO.Stream stream, Mono.Cecil.WriterParameters parameters) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.ModuleDefinition.Write (System.String fileName, Mono.Cecil.WriterParameters parameters) [0x00000] in <filename unknown>:0 
      at Mono.Cecil.AssemblyDefinition.Write (System.String fileName, Mono.Cecil.WriterParameters parameters) [0x00000] in <filename unknown>:0 
      at Unity.UNetWeaver.Weaver.Weave (System.String assName, IEnumerable`1 dependencies, IAssemblyResolver assemblyResolver, System.String unityEngineDLLPath, System.String unityUNetDLLPath, System.String outputDir) [0x00212] in C:\buildslave\unity\build\Extensions\Networking\Weaver\UNetWeaver.cs:1733 
      at Unity.UNetWeaver.Weaver.WeaveAssemblies (IEnumerable`1 assemblies, IEnumerable`1 dependencies, IAssemblyResolver assemblyResolver, System.String outputDir, System.String unityEngineDLLPath, System.String unityUNetDLLPath) [0x00062] in C:\buildslave\unity\build\Extensions\Networking\Weaver\UNetWeaver.cs:1757 
    UnityEngine.Debug:LogError(Object)
    Unity.UNetWeaver.Log:Error(String) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/Program.cs:20)
    Unity.UNetWeaver.Weaver:WeaveAssemblies(IEnumerable`1, IEnumerable`1, IAssemblyResolver, String, String, String) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1764)
    Unity.UNetWeaver.Program:Process(String, String, String, String[], String[], IAssemblyResolver, Action`1, Action`1) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/Program.cs:34)
    UnityEditor.Scripting.Serialization.Weaver:WeaveUnetFromEditor(String, String, String, String, Boolean)
    
   

2.    Failure generating network code.
      UnityEditor.Scripting.Serialization.Weaver:WeaveUnetFromEditor(String, String, String, String, Boolean)
   
   

3.  error CS0016: Could not write to file `Temp/Assembly-CSharp.dll', cause: Sharing violation on path F:\...\Temp\Assembly-CSharp.dll.mdb
   
      Compilation failed: 1 error(s), 0 warnings
   
   

I don't really know what to do so please help.