Texas Code of Criminal Procedure article 1.15 requires "the State to introduce evidence into the record showing the guilt of the defendant." TEX. R. CRIM P. ANN. art. 1.15 (Vernon Supp. 2000). The evidence may be stipulated by the defendant. Id. However "such waiver and consent to stipulations must be approved by the court in writing, and be filed in the file of the papers of the cause." Id. This statute is mandatory and should be strictly followed. McClain v. State, 730 S.W.2d 739, 742 (Tex. Crim. App. 1987). Under article 1.15, the stipulation becomes a "writing of the court" only when the trial court places his signature on the consent to stipulate. Id. A judgment based on a stipulation that has been presented without the judge's signature, in violation of the statute, is fundamental error that requires reversal, but not acquittal. Id. at 743; Young v. State, 648 S.W.2d 6, 7 (Tex. Crim. App. 1983). The consent of the accused to stipulate is what must be approved in writing by the court, and not the stipulations. McClain, 730 S.W.2d at 742. Moreover, failure to comply with this mandatory statute cannot be waived by the accused. McClain, 730 S.W.2d at 743. A judicial confession alone is sufficient evidence to sustain a conviction upon a guilty plea under article 1.15. Dinnery v. State, 592 S.W.2d 343, 353 (Tex. Crim. App. 1979). The judicial confession may take the form of an affirmative acknowledgment by the defendant that the indictment was true and correct. Id. at 352.