Error triggering showMgr.GetEpisodeInfo(strShow, intSeason, intEpisode)

[JontheCoder]

When I call the above using the following code, I get the (following) error message
Method not found: 'System.String ServiceStack.Text.WebRequestExtensions.GetJsonFromUrl(System.String, System.Action1<System.Net.HttpWebRequest>, System.Action1<System.Net.HttpWebResponse>)'.'

Triggered using
ShowInformationManager showMgr = new ShowInformationManager();
TVEpisodeInfo episode = showMgr.GetEpisodeInfo(strShow, intSeason, intEpisode);

where strShow="Power" (as an example), intSeason=5, intEpisode=6

I get the same error following your example (Once upon a time)

Please advise what I'm missing?
using System;
using System.IO;
using System.Configuration;
using System.Net;
using ShowInfo;
using ShowInfoProvider;