Can someone please explain the parameters in the following overload of EditUrl:

"Public Function EditUrl(ByVal KeyName As String, ByVal KeyValue As String, ByVal ControlKey As String, ByVal ParamArray AdditionalParameters() As String) As String"

I mean every control (except the primary View Control) has a key associated to it. So, what does KeyName or KeyValue signify here??? What should be passed as their values?

Also, what are AdditionalParameters? Is there any special syntax to be used for strings being passed to AdditionalParameters???
 Are they passed to the destination page in its QueryString?? (In my case, I tried to pass "Action=Add" as Additional Parameter, but could not retrieve anything like that on the destination control)!!!

You want to use EditUrl when you are navigating to a sub control of your current control (using a Control Key).  If you are navigating anywhere else, use NavigateUrl.  The main difference, (aside from the different signatures) is that EditUrl will include mid=(your module's ID) in the querystring so that DNN knows how to load the control you are trying to load based on the control key.

The most basic scenario for EditUrl is where you just need to get to a sub control with a control key of "Edit".  That's where you'll just use EditUrl() without any parameters.  Say that the control key is "DisplayOptions," then use EditUrl("DisplayOptions").

Now, the "tricky" part is when you want to pass custom parameters.  For the first parameter, use those KeyName, and KeyValue parameters (so, EditUrl("Action", "Add", "DisplayOptions") ).  If you have other parameters, use the AdditionalParamters array, like so: EditUrl("Action", "Add", "DisplayOptions", "pid=1", "lid=2", "xid=3").  The reason this seems kind of weird is that EditUrl is written with the edit scenario in mind, where you'd do something like EditUrl("itemId", 3, "EditItem"), where you often need to keep track of just one parameter (the item you are editing).

All of these parameters should show up on the querystring (all EditUrl is doing, after all, is creating a URL).  In the receiving control, you should be able to get at them by calling Request.QueryString("Action"), etc.

If that isn't working, take a look at the URL that EditUrl is generating, and see whether those values are getting put on it.

Hope that helps,