The best overloaded method has some invalid arguments

foreach (var item in finalList)
                    {
                        MatchInfo matchInfo = new MatchInfo();
                        matchInfo.CId = Convert.ToInt32(splitEnt[0]);
                        matchInfo.SId = Convert.ToInt32(splitEnt[1]);
                        matchInfo.SLabel = item.SLabel;
                        string[] Hours = item.HourString.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries);
                        matchInfo.Hours = new List<byte>();
                        foreach (var h in Hours)
                            matchInfo.Hours.Add(Convert.ToByte(h));
                        matchInfo.Duration = item.Duration;
                        matchInfo.Csts = new List<double>();
                        var query = from sp in studentInfoList
                                    where sp.CId == matchInfo.CId
                                    select sp;
                        string[] csts = item.CstString.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries);
                        foreach (var s in csts)
                            matchInfo.Channels.Add(ConvertChannelToFrequency(Convert.ToInt32(s), matchInfo.SId, query.ToList()));
                        matchInfo.Hours = matchInfo.Hours.Distinct().ToList();
                        matchInfo.Csts = matchInfo.Csts.Distinct().ToList();
                        match.Matches.Add(matchInfo);
                    }

public static double ConvertcstToFreq(int cst, short dsp, List<StudentInfo> studentList)
        {
            double freq = (double)cst * 0.10 + (double)studentist[dsp].Bst / 2500.0;
            return freq;
        }

The best overloaded method match for 'Student.Web.Services.EventService.
ConvertChannelToFrequency(int, short, System.Collections.Generic.List
<Student.Web.Services.StudentInfo>)' has some invalid arguments