Index was outside the bounds of the array. Json string

List lstSSn = serializer.Deserialize<List>(s); I got the Index was outside the bounds of the array of a Json String. 

Why? Is there anything wrong with the following JsonString I posted ...one works the other not...
[{"RowNo":"1","TreeId":"18","TreeText":"","SeriesCode":"Com ABC/MV-C","Description":"","RunningNoFormat":"","RunningStartingNo":"","EndingNo":"","LastDateUsed":"","RunningLastNo":"0","SeriesId":"-1"}]   = ERROR
[{"RowNo":"1","TreeId":"18","TreeText":"","SeriesCode":"Com ABC/MV-C","Description":"test","RunningNoFormat":"00001","RunningStartingNo& ...