Our statistics show that the campaigns that fail are those that start slowly. On the contrary, campaigns that have a good start are less likely to fail.
Faced with this observation, we allocate by default the clicks to the campaigns with the slowest progress, in order to significantly reduce the number of failed campaigns.
However, if you wish to attribute your click to a particular campaign, or change your default settings related to clicks allocation, this is entirely possible. To do so, we invite you to follow the detailed instructions provided in this article: How do I choose which campaign my click will be allocated to?