Get Value from list of objects

Question

List<AttributeNamesValues> Keyvalues = new List<AttributeNamesValues>();

AttributeNamesValues keyvalue = new AttributeNamesValues();

keyvalue.AName = "Gross Volume";

keyvalue.AValue = "as100";

Keyvalues.Add(keyvalue);

keyvalue.AName = "Clean Volume";

keyvalue.AValue = "as120";

Keyvalues.Add(keyvalue);

keyvalue.AName = "Clean Volume%";

keyvalue.AValue = "asclean";

Keyvalues.Add(keyvalue);

List<AttributeKeyValues> attributeNames = (from main in db.Attributes_Sub

where attribute_subid.Contains(main.Id)

select new AttributeKeyValues

{

MainName = main.Attributes_Relation.Select(x => x.Attributes_Main.AttributeName).FirstOrDefault().ToString(),

SubName = main.AttributeSubName,

Value= Keyvalues.Where(item => item.AName == main.AttributeSubName).Select(x1=>x1.AValue).FirstOrDefault().ToString()

}).ToList();

 

I am getting error at while getting Value please help me