Very sorry for the delay in getting back to you. I do see some issues in the screen shots you sent, and hopefully fixing them will fix your issues.
In your object configuration, it looks like you created an object type of "blog" on Facebook. Since you created it (it's not a pre-defined type by Facebook), you should UN-check the "Built-In Facebook Object" box. Alternatively, you may want to switch to using the built-in "article" type from Facebook. Either option works.
In your action configuration, you created a custom action of type "comment" on Facebook. You properly have the "Built-In Facebook Object" box un-checked. However, you've also included the namespace in the type. The type box should just be "comment". JFBConnect will take care of adding the namespace.
Try updating those values and hopefully you'll get something going. If not, let us know. I'll be much quicker to respond next time, and again apologize for the delay.
Thanks,
Alex