Market Registration of EA Unable to Validate

You are looking at the report on a mobile phone and unable to see the right-hand side of the report, which probably shows the OrderSend failing. Read the report on your PC with a normal desktop browser to see the full text (or at least flip your phone into landscape and zoom out).

Also, at the end of the report there is a link "The checks a trading robot must pass before publication in the Market". Click on it, read it and verify that your EA is following those guidelines.

For your screenshot with an Error 131 and it also has a link on "How to fix it". So follow up on it and fix your EA accordingly.

In regards to volume, you have to check the contract specification of the symbol and limit your volume to the minimum, maximum and step that is allowed for the symbol.

// Variables for symbol volume conditions
   double
      dbLotsMinimum = SymbolInfoDouble( _Symbol, SYMBOL_VOLUME_MIN  ),
      dbLotsMaximum = SymbolInfoDouble( _Symbol, SYMBOL_VOLUME_MAX  ),
      dbLotsStep    = SymbolInfoDouble( _Symbol, SYMBOL_VOLUME_STEP );
       
// Adjust volume for allowable conditions
   dbLots = fmin(  dbLotsMaximum,                           // Prevent too greater volume
            fmax(  dbLotsMinimum,                           // Prevent too smaller volume
            round( dbLots / dbLotsStep ) * dbLotsStep ) );  // Align to step value