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How to Debug a NinjaTrader Trade Copier with AI

The CrossTrade trade copier moves orders from a leader to one or more followers. When a follower misses, the broker UI usually shows nothing. The CrossTrade Add-On activity log holds the truth. With CrossTrade MCP, an AI agent reads both leader and follower logs in one conversation and points at the gap.

Direct answer​

Authenticate with mcp:read. Run this prompt with the leader, follower, and time window:

For leader <leader_account> and follower <follower_account> between <start> and
<end>:
1. GetActivityLog for both accounts.
2. ListOrders and ListExecutions for both in the same window.
3. ListPositions for both.
4. Build a single chronological timeline.
5. Identify the step where the follower path broke.
6. State the verbatim rejection reason if any.
7. Tell me the most likely root cause.
8. Suggest a one-line check the trader can run before the next session.
Do not place, cancel, modify, or flatten anything.

The agent reconstructs the timeline. The rejection reason is usually one line, like "follower rejected: max contracts (existing 4 + routed 2 > limit 5)".

Common copier failures​

PatternCause
Leader filled, follower rejectedMax contracts on follower account
Follower late or out of syncRouting delay or follower broker latency
Wrong quantity on followerCopier ratio or per-account override
Follower took the wrong sideConfiguration error in copier mapping
Two accounts diverged silently over timeManual trades on one account, or copier-disabled window

Prerequisites​

RequirementDetail
CrossTrade subscriptionElite
CrossTrade Add-Onv1.13.0 or higher
MCP clientAny
Scopemcp:read

Step 1: Confirm the symptom​

Before running the agent, note the leader fill time and the follower account that missed. A 5-minute window around the leader fill is usually enough.

Step 2: Run the diagnostic prompt​

Paste the prompt above with your specific accounts and window.

Step 3: Read the timeline​

Look for the step where the follower path stops. Typical patterns:

14:32:09.812  LEADER     order placed
14:32:10.041  LEADER     fill confirmed, 2 contracts at 5240.25
14:32:10.044  copier     leader fill received
14:32:10.047  copier     follower routing started
14:32:10.121  copier     follower rejected: max contracts (existing 4 + routed 2 > limit 5)
14:32:10.121  FOLLOWER   no order placed

The verbatim rejection reason is what you want. It usually tells you exactly which check fired.

How to spot each cause in the timeline​

Root causeIndicator in the timeline
Max contractsRejection reason explicitly states max contracts.
Daily loss lockoutRejection or no order; account summary shows lockout.
Account disconnectedGetConnections shows disconnected; no follower routing entry at all.
Symbol mappingMarketInfo differs across accounts; routing entry references the wrong instrument.
Existing position conflictListPositions shows opposite side or already-over-limit qty before the leader fill.
Copier configurationRouted quantity differs from leader; no rejection.
Bracket/ATM mismatchLeader entry uses bracket; follower has none configured.

Worked example​

A typical case looks like this when you trace it end to end:

  • Leader APEX1234 filled long 2 MES at 5240.25.
  • Follower APEX1235 already held 4 MES from earlier in the session.
  • Activity log: follower rejected: max contracts (already at 5/5).
  • Root cause: follower APEX1235 was configured at max 5 contracts; the copier was routing the leader's 2 on top of an existing 4, total 6, exceeding the limit.
  • Fix: either raise max contracts on APEX1235 if firm rules allow, or close the existing position before letting the copier replicate.

The agent's job is to extract the timeline and point at the line. The fix is your judgment.

Step 4: Fix the underlying issue​

CauseFix
Max contracts on followerReduce existing position or raise the per-account limit (if firm rules allow)
Follower disconnectedReconnect the follower account in NT8
Symbol mappingConfirm both accounts subscribe to the same instrument; update copier mapping
Existing position conflictFlatten the conflicting position manually
Copier ratio mismatchUpdate copier configuration in CrossTrade
Bracket/ATM mismatchMake sure both accounts have compatible bracket settings

Step 5: Verify with a test signal​

After the fix, fire a controlled leader order on Sim101 (or whatever non-funded environment you use for tests) and re-run the diagnostic prompt. The agent should report the follower path matched.

Funded futures considerations​

  • Apex prohibits automation entirely; a copier that routes to an Apex follower may violate firm rules even when CrossTrade can technically perform the route. Verify the firm's automation policy.
  • Some firms prohibit cross-firm copying. Verify before you rely on it.
  • Per-account max contracts on funded accounts usually cannot be raised without firm approval.