Hi I have configured UGC and I am getting the above error and also unable to save from presentation side to DB. 

    [Info] Loaded Blueprint chain with 9 publications in 55 milliseconds
    w3wp.exe Error: 0 : [UGC.PublicationExtender] Failed processing the request : System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
     at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
     at Tridion.UGC.DataExtenders.PublicationExtender.ProcessRequest(XmlTextReader reader, PipelineContext context)
    w3wp.exe Error: 0 : [UGC.PublicationExtender] Failed processing the request : System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
     at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
     at Tridion.UGC.DataExtenders.PublicationExtender.ProcessRequest(XmlTextReader reader, PipelineContext context)

UPDATE 14/1:
I checked the connection between CM + odata2 (moderator side webservice) and it seems to work fine except for the occasional "Couldn't retrieve data from 1 datasource" on the CM explorer. I know it works because I can create and view comments on the component's Comments tab  in CMS explorer. However on the presentation side + odata1 (visior web service), I am not able to fetch the comments. It looks like the website is not making the webservice call to odata1. Also when I view the generated HTML format for the page, after this statement <ugc:comments itemuri="tcm:10-4952">, I don't see the generated tag to fetch the contents <ugc:contextvariable var="ugccomment.content"></ugc:contextvariable>. 
This is how the tcdl code looks like  <tcdl:ContextVariable var="ugcComment.content"/> which I have taken from the default UGC dreamweaver Template.
Am I missing something.