Is a certificate of probable cause sufficient to grant appellate review of a claim?

Furthermore, "[t]he trial courts issuance of a certificate of probable cause to permit appellate review of this issue does not change our conclusion. A certificate of probable cause cannot render reviewable a claim that is otherwise not cognizable on appeal from a guilty plea. [Citations.]" ( People v. Collins (2004) 115 Cal.App.4th 137, 149, 8 Cal.Rptr.3d 731.) Judge Goethalss certificate of probable cause is wholly ineffective to confer jurisdiction on the appellate court when the issue proposed to be raised is in fact not appealable. " Obtaining a certificate of probable cause does not make cognizable those issues which have been waived by a plea of guilty. " ( People v. Hernandez (1992) 6 Cal.App.4th 1355, 1361, 8 Cal.Rptr.2d 324.)