Might just be an IG issue. Last week it stopped displaying charts (bit of an issue in the middle of a trade!) and I started receiving emails about positions other people were opening and closing in my inbox.
There should be enough shares sloshing about in ABM to be able to buy that amount or more.
Notice that:
Taruga has entered an agreement with local company Madini Minerals to acquire a 70% interest in a tenement in the Kolwezi Mining District and three in the Lubumbashi Mining District.