I don't know why the trade volume is invalid. Maybe your broker has a minimum order volume and the trades are below it. You can contact your broker and ask him about that. All brokers I know accept trade volumes down to 1 lot, but if there is a minimum volume, it should be displayed on the broker's website.

The "0.05" means that MT4 does not use lots, but "standard lots". On a micro lot account, one "standard lot" is 100 lots. You can find details about MT4 units in your MT4 manual.