Dissolves very poorly on

As the years consumed by my Whey Isolate by PowerBar is apparently no longer in production, I have now tried out new products.
I rated this only flavor and solubility. Of the ingredients of this product's relatively good and includes eg aspartame etc.
The big problem here is for me, however, that this product is not drinkable.
I tried it in a 500ml shaker with 250ml milk. On the one hand it foams so extreme that after a short period of Shaker is so full that one more shaking is no longer possible and, secondly, the powder does not dissolve. It caused countless small lumps the mouthfeel both very ugly as well as the burst drink and a spoil drinking. In addition, some of the powder at the bottom of the shaker sticks.
The principle of the taste perfectly fine (apart from the lumps). Here are relatively few flavors available so that the product tastes slightly of vanilla.