I apologize Jac... The pink block can be in any of the 7 lower spots and not the 3 upper ones. Try the number 4 pink (counting from left to right). Otherwise it is great.
In order to increase difficulty level I suggest using more icy blocks (i think 14-15 out of the 20 is a good ratio) and grouping some blocks. It needs a lot of work (as is, it is not quite straightforward which could be grouped and which could not) but I think it is worth it. In any case it seems a decent and well designed lvl.