Trying to send byte array to server yields error: Trying to send command for object without authorit

I have no idea why this is happening. I'm trying to send a byte array from my client to my server across a local network and I'm getting the error `Trying to send command for object without authority.` when multiple clients are connected to the server simultaneously. If I'm creating an object that's a serialized byte array, how do give it authority?

The full error I'm getting is

Trying to send command for object without authority.
UnityEngine.Networking.NetworkBehaviour:SendCommandInternal(NetworkWriter, Int32, String)
Network_Transmitter:CallCmdPrepareToReceiveBytes(Int32, Int32)
<DoSendBytes>c__Iterator0:MoveNext() (at Assets/Scripts/Networking/Network_Transmitter.cs:46)
UnityEngine.MonoBehaviour:StartCoroutine(IEnumerator)
Player_DatarepareServerData() (at Assets/Scripts/Player/Player_Data.cs:77)
Event_Manager:SendTextureData() (at Assets/Scripts/Event_Manager.cs:31)
Game_UI:SendData() (at Assets/Scripts/Game_UI.cs:39)
UnityEngine.EventSystems.EventSystem:Update()

and the functions where the error is occurring is here:

Code (CSharp):

1.     [Client]
2.         public IEnumerator DoSendBytes(int transmissionId, byte[] data)
3.         {
4.             Debug.Assert(!clientTransmissionIds.Contains(transmissionId));
5.             Debug.Log(LOG_PREFIX + "SendBytesToClients processId=" + transmissionId + " | datasize=" + data.Length);
6.  
7.             //tell server that he is going to receive some data and tell him how much it will be.
8.             CmdPrepareToReceiveBytes(transmissionId, data.Length);
9.             yield return null;
10.  
11.             //begin transmission of data. send chunks of 'bufferSize' until completely transmitted.
12.             clientTransmissionIds.Add(transmissionId);
13.             TransmissionData dataToTransmit = new TransmissionData(data);
14.             int bufferSize = defaultBufferSize;
15.             while (dataToTransmit.curDataIndex < dataToTransmit.data.Length - 1)
16.             {
17.                 //determine the remaining amount of bytes, still need to be sent.
18.                 int remaining = dataToTransmit.data.Length - dataToTransmit.curDataIndex;
19.                 if (remaining < bufferSize)
20.                     bufferSize = remaining;
21.  
22.                 //prepare the chunk of data which will be sent in this iteration
23.                 byte[] buffer = new byte[bufferSize];
24.                 System.Array.Copy(dataToTransmit.data, dataToTransmit.curDataIndex, buffer, 0, bufferSize);
25.  
26.                 //send the chunk
27.                 CmdReceiveBytes(transmissionId, buffer);
28.                 dataToTransmit.curDataIndex += bufferSize;
29.  
30.                 yield return null;
31.  
32.                 if (null != OnDataFragmentSent)
33.                     OnDataFragmentSent.Invoke(transmissionId, buffer);
34.             }
35.  
36.             //transmission complete.
37.             clientTransmissionIds.Remove(transmissionId);
38.  
39.             if (null != OnDataComepletelySent)
40.                 OnDataComepletelySent.Invoke(transmissionId, dataToTransmit.data);
41.         }
42.  
43.         [Command]
44.         private void CmdPrepareToReceiveBytes(int transmissionId, int expectedSize)
45.         {
46.             if (serverTransmissionData.ContainsKey(transmissionId))
47.                 return;
48.  
49.             //prepare data array which will be filled chunk by chunk by the received data
50.             TransmissionData receivingData = new TransmissionData(new byte[expectedSize]);
51.             serverTransmissionData.Add(transmissionId, receivingData);
52.         }
53.  
54.         //use reliable sequenced channel to ensure bytes are sent in correct order
55.         [Command]
56.         private void CmdReceiveBytes(int transmissionId, byte[] recBuffer)
57.         {
58.             //already completely received or not prepared?
59.             if (!serverTransmissionData.ContainsKey(transmissionId))
60.                 return;
61.  
62.             //copy received data into prepared array and remember current dataposition
63.             TransmissionData dataToReceive = serverTransmissionData[transmissionId];
64.             System.Array.Copy(recBuffer, 0, dataToReceive.data, dataToReceive.curDataIndex, recBuffer.Length);
65.             dataToReceive.curDataIndex += recBuffer.Length;
66.  
67.             if (null != OnDataFragmentReceived)
68.                 OnDataFragmentReceived(transmissionId, recBuffer);
69.  
70.             if (dataToReceive.curDataIndex < dataToReceive.data.Length - 1)
71.                 //current data not completely received
72.                 return;
73.  
74.             //current data completely received
75.             Debug.Log(LOG_PREFIX + "Completely Received Data at transmissionId=" + transmissionId);
76.             serverTransmissionData.Remove(transmissionId);
77.  
78.             if (null != OnDataCompletelyReceived)
79.                 OnDataCompletelyReceived.Invoke(transmissionId, dataToReceive.data);
80.         }

The entire project can be found here: https://github.com/kenmarold/HLAPI-Prototype