Summary: Learn how to diagnose and fix common MT4 EA loading failures and DLL errors with our step-by-step troubleshooting guide.
1. Check EA File Placement: Open your MT4 data folder via `File > Open Data Folder` (screenshot: located at top menu bar of MT4 main interface). Navigate to `MQL4 > Experts` and confirm your .ex4/.mq4 EA file is saved in this folder. If placed incorrectly, move the file to the correct directory and restart MT4.
2. Verify Auto-Trading is Enabled: Check the "Auto-Trading" button on MT4's top navigation bar (screenshot: toolbar area next to the new order button). If the button is gray, click to enable it. EA cannot run if auto-trading is disabled globally.
3. Check DLL Permission Settings: Open the EA settings window by double-clicking the EA attached to the chart (screenshot: pop-up settings window after double-clicking EA). Go to the "Common" tab, check the option "Allow DLL imports". Unchecking this option will cause DLL loading failures.
4. Confirm File Compatibility: Make sure your EA is compiled for MT4 (MQL4) instead of MT5 (MQL5). MQL5 EAs cannot run on MT4 and will cause loading errors. Recompile the EA in MetaEditor for your MT4 version if needed.
5. Restart MT4 After Changes: After adjusting any settings or moving files, completely close and restart MT4 to apply changes. Check the "Experts" tab in the Terminal window to confirm if the EA loaded successfully.
Reference: MetaQuotes Official MT4 Help Documentation