Handling and/or in lambda expression

   I have a query in my remote method that is using lambda expressions. The Where clause has both ands and ors in it so I need to use multiple parentheses to achieve the right answer. But it doesn't seem to like multiples parentheses.

public static EmplRange GetEmplRangeWithoutWage(EntityManager manager, Member member, DateTime? startDate, DateTime? endDate)

{
var query = manager.GetQuery<EmplRange>()

.Where((er => er.TradeCd == member.TradeCd || er.TradeCd == "ALL") && (er.EffDate <= endDate && (er.EndDate >= startDate || er.EndDate == null))

.Select(er => er);