Error on SPWebApplication.WebService.ApplyWeyConfigModifications

Question

I've been trying to add a line to my web.config through a EventReceiver on my webpart's Feature. I tried to follow some 'tutorials' (this, this and this). It wasn't working, but at least i could deploy the solution.

Sometimes it would delete everything on my web.config and leave only the line that i wanted to add. It was a simple line on <configuration><appSettings><add key="searchPath" value="http://myVirtualMachineSearchPath" />

After the update, it would leave me empty with just that one single line on the web.config.

Right now, my code is this:

public override void FeatureActivated(SPFeatureReceiverProperties properties)
        {
            InsertWebConfigEntries(properties);
        }

        //add all web.config entries 
        private void InsertWebConfigEntries(SPFeatureReceiverProperties properties)
        {
            if (!CheckEntries(properties))
            {
                using (SPSite site = properties.Feature.Parent as SPSite)
                {
                    SPWebConfigModification dsEntry = GenerateWebConfigEntry("New config key", "configuration/appSettings",
                        "<add key=\"searchPath\" value=\"http://myVirtualMachineSearchPath\" />", 100);

                    SPWebApplication currentWebApp = site.WebApplication;

                    currentWebApp.WebConfigModifications.Add(dsEntry);
                    currentWebApp.WebService.ApplyWebConfigModifications();
                    currentWebApp.Update();
                }
            }
        }

        //check if the web.config entry exists. If you don't call this method you will get duplicate entries 
        private bool CheckEntries(SPFeatureReceiverProperties properties)
        {
            using (SPSite site = properties.Feature.Parent as SPSite)
            {
                SPWebApplication currentWebApp = site.WebApplication;

                Collection<SPWebConfigModification> webConfigEntries = currentWebApp.WebConfigModifications;

                foreach (SPWebConfigModification entry in webConfigEntries)
                {
                    if (entry.Owner == "Owner")
                    {
                        return true;
                    }
                }

                return false;
            }
        }

        //new web.config entry 
        private SPWebConfigModification GenerateWebConfigEntry(string modName, string sXpath, string sKey, uint iSequence)
        {
            SPWebConfigModification configMod = new SPWebConfigModification(modName, sXpath);
            configMod.Type = SPWebConfigModification.SPWebConfigModificationType.EnsureChildNode;
            configMod.Name = string.Format("add[@name='{0}']", modName);
            configMod.Owner = "Owner";

            configMod.Value = sKey;
            configMod.Sequence = iSequence;

            return configMod;
        } 

But now, when I try to deploy the solution, it gives me an error:

Error occurred in deployment step 'Activate Features': Failed to apply web.config modifications to Web application '3f79bb09-9e0f-4aed-a400-5debe6346440'.
Failed to apply web.config modifications to file 'C:\inetpub\wwwroot\wss\VirtualDirectories\80\web.config'.
Failed to apply a web.config modification to file 'C:\inetpub\wwwroot\wss\VirtualDirectories\80\web.config'.  
The specified node "configuration/appSettings" was not found in the web.config file.

When i debug the code, my SPWebApplication.WebConfigModifications already contains 18 elements that i added on my previous attempts, but i deleted that code and for some reason, i can't evoke the WebConfigModifications.Clear() method with success, every time i try to use the SPWebApplication.Update() it gives me the error above, even when i don't add any other SPWebConfigModification.

Anyone have a idea of what I can do to work with this issue?

I'm sorry if the post is a little confusing, but I'm pretty lost at the moment.