Why were settlers from the US now Mexican citizens upset with government in 1835?

When this area became part of Mexico, the Anglos were promised they could keep their slaves and their legal/political system under the Treaty of Velasco. However, the Mexican government passed laws making slavery illegal, and Mexican law would prevail. It seemed obvious that the Anglos would be treated as 2nd class citizens. There were a few other points of contention in the 1820s and early 1830s, but this was really the major one that led to the Texas Revolution.