'Cannot await on Task<string>' (PCL Xamarin Studio)

I'm trying to write the following method: ``` public async Task<string> GetJson(string url, Dictionary<string,string> parameters = null){ // parameters? if (parameters != null) { if (parameters.Count > 0) { url += "?"; foreach(var key in parameters.Keys){ // add parameter to url url += String.Format("{0}={1}", key, parameters[key]); // more parameters? if(!parameters.Keys.Last ().Equals(key)){ url += "&"; } } } } // send request var uri = new Uri(url); var req = new HttpClient(); Task<string> getJsonTask = req.GetStringAsync(uri); // EXCEPTION : 'Cannot await on Task<string>' return await getJsonTask; } ``` I get an error at compilation time. I don't think the problem is the syntax. I think is a dependencies issue. My references are: I added them using Nuget. Any ideas about what could be the issue? Thanks in advance. UPDATE Suggested by Selman22: ``` public async Task<string> GetJson(string url, Dictionary<string,string> parameters = null){ // ... return await req.GetStringAsync(uri); // Same exception } ``` Suggested by Kenneth: ``` public Task<string> GetJson(string url, Dictionary<string,string> parameters = null){ // ... return req.GetStringAsync(uri); // no problems here } // Later when trying to invoke GetJson public async Task<List<Station>> GetStations(){ var url = String.Format( "?{0}_id{1}&_render=json", DublinBikeDataProvider.BASE_URL, DublinBikeDataProvider.STATIONS ); var json = await this._httpClient.GetJson(url); // same exception return this.ParseStations(json); } ```