Code First EF : executing stored procedure

I am getting this error message:
The data reader has more than one field. Multiple fields are not valid for EDM primitive or enumeration types

The stored procedure takes three parameters, two of them being varchar and the last being int

All the parameters have values, when I execute stored procedure manually with the same values it ran successfully.

var output = Context.DbQuerySingle<string>(query, sqlParams.ToArray());