I'm fairly new to Linq and EF. Having problems comparing strings in Linq entities and SQL : Any way the comparison of strings is incorrect?

I've already tried the String.Equals or CompareTo but those return boolean values, i read for Linq the comparison String == string is like a WHERE statement from SQL. 

public IHttpActionResult GetMultifiberResult(string partNumber)
        {

        var list = db.MultifiberResults.Where(s => s.PartNumber == 
                    partNumber).ToList();

      

            return Ok(list);
        }

list should return a bunch of values where the column PartNumber from the DB is equal to parameter partNumber. When I search using int comparison it does find matches in an int column but not with varchar columns. Controller always returns empty and the count is 0.