Not able to register preferences on mozilla using registerFactoryLocation

I m XPCOM component for registering the preferences on mozilla firefox but it is not getting reflected in prefs.js file. Anything more i need to use apart from registerFactoryLocation code.... Thanks in advance :)

ya sure,I have developed an XPI,in that in comonents folder I have added a mymanager.js file. In that I have creted a compo开发者_C百科nent using the code like.......... http://kb.mozillazine.org/Implementing_XPCOM_components_in_JavaScript but this code does not able to add the _prority preferece to mozilla firefox preferences(prefs.js) file. I need to do anything more to register the preference...

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Although your extension can register preferences, prefs.js only contains changed preferences, so they won't automatically appear there.