In Morales v. State, 640 S.W.2d 273, 275 (Tex. Crim. App. 1982), the court of criminal appeals held that a search of an entire multi- unit dwelling was illegal because the warrant only called for the search of one of the dwellings. Id. Morales is distinguishable because it dealt with the inaccurate description of the dwelling contained in the warrant. Id. Nevertheless, the principle is the same: for a search to be legal, the scope must be limited to the description contained in the warrant. See id. A valid warrant based on probable cause is necessary to conduct a search unless one of the exceptions to the warrant requirement is appropriate. Id. The purpose of a warrant is: (1) to ensure that there is adequate probable cause to search and (2) to prevent the mistaken execution of the warrant against an innocent third party.