problem with extended_valid_elements and custom elements in tinymce

Question

I have used

extended_valid_elements : "info,second,tittle,defalut",
custom_elements: "info,second,tittle,defalut",

for adding new tags to tinymce editor.The contents in tinymce editor is something like <tittle>contents here </tittle>.i can save the content as it is in both browser.when i am adding external css for editor due to custom_elements: "info,second,tittle,defalut",the css class is not applying to the editor.if i remove this,the css will apply in the editor and i can save the content as it is in mozilla.Due to removing custom_elements the content is saving like <tittle></tittle> contents here.How i can solve this problem.Thanks in advace.