Which is the Java datatype of the VO attribute "CkAprobado"? Your button binding is configured as if the datatype is either java.lang.Boolean or java.lang.String containing "true" / "false" strings. If the datatype/values are other, you should either modify the button binding or use a JSF converter to convert the values to boolean (e.g. true/false) ones. For example, if your VO attribute contains character values "Y" / "N" (where "Y" maps to a checked state), then you should modify the binding as follows:
It should work then if the attribute CkAprobado contains the correct boolean value. Are you sure that the PanelFormLayout is refreshed properly? I see <tt><af:panelFormLayout partialTriggers="t1:ot1"></tt>. Supposing that the table's ID is "t1", what is "t1:ot1" then? Why have not you set <tt>partialTriggers="t1"</tt>? Would you post the table tags (that are supposed to fire PPR refreshing the PanelFormLayout)?