From Chabad.org: Bilaam sent word with Balak’s messengers that G‑d doesn’t permit him to go with them. So Balak sent more prestigious messengers to Balaam, promising him great riches in return for his services. Once again G‑d appeared to Balaam. This time G‑d allowed Balaam to go — provided that he only speak the words which G‑d dictates to him.
In this Aliya we see the ups and downs of trying to curse the Jews. On one hand Bilaam was displaying an arrogance that he was unwilling to travel with lowly messengers, and he tells the next set of more important messengers that he needs to receive permission from G-d to curse the Jews, and that he’ll ask again. But alas, persistence (on Balak’s part) pays off because the second time G-d talks to him in his dream, he grants him permission to travel, although he still doesn’t have permission to curse. In his mind, though, Bilaam sees it as a minor victory, and if he persists, there might be others. Such is human nature, especially children and our evil inclinations, to look for minor victories in search of others.