asp.net error page on Feature Activation

I'm having a problem activating a feature I have written and installed.
This feature should create a timer job when activated, the timer job simply queries a list and sends emails where applicable.

I am sure my problem is down to scope but I am not sure how to change it or what it should be.
The code (under execute) is hard coded to point to a single list therefore this feature and timer job reference this single list only. It is not necessary to have the activate feature button anywhere.

However: I have tried scoping the feature to both web and webapplication level and get the same problem.
Here is my feature activated code:

public override void FeatureActivated(SPFeatureReceiverProperties properties)
        {
            try
            {
                SPSecurity.RunWithElevatedPrivileges(delegate
                {
                    SPWeb site;
                    SPWebApplication parentWebApp = (SPWebApplication)properties.Feature.Parent;
                    site = ((SPSite)properties.Feature.Parent).RootWeb;
                    DeleteJob(JobName, parentWebApp);
                    CreateJob(parentWebApp);
                });
            }
            catch (Exception)
            {
                throw;
            }
        }

        public bool CreateJob(SPWebApplication site)
        {
            bool jobCreated = false;

            try
            {
                Reminders job = new Reminders(JobName, site);
                SPMinuteSchedule schedule = new SPMinuteSchedule();
                schedule.BeginSecond = 0;
                schedule.EndSecond = 59;
                schedule.Interval = 15;
                job.Schedule = schedule;
                job.Update();
            }
            catch (Exception)
            {

                throw;
            }
            return jobCreated;
        }

        public bool DeleteJob(string jobName, SPWebApplication site)
        {
            bool jobdeleted = false;
            try
            {
                foreach (SPJobDefinition job in site.JobDefinitions)
                {
                    if (job.Name == jobName)
                    {
                        job.Delete();
                        jobdeleted = true;
                    }
                }
            }
            catch (Exception)
            {

                return jobdeleted;
            }

            return jobdeleted;
        } 

I am using: install-spsolution -identity IncidentReminders.wsp -gacdeployment and then restarting the timer service to make sure it also gets deployed to the app server.

Can someone see where I have gone wrong?
Once I have the code sorted I will look at making this a hidden feature as it's only purpose is to create a timer job and has no place being in the list of site feature buttons on every site in the web app