>>I was wrong in telling you the problem. The problem with your code is that there is no Where operator on decimal.
>>
>>Since I can not figure your syntax, I am trying to find other samples. Unfortunately, I can not so far make that one I found work either.
>>
>>I am reading more into the syntax and looking into various samples trying to adapt to my case.
>
>Is extension nullable? Will it ever be null? If it isn't in decimal format convert it to decimal. Show me the actual error message.

The error I am getting in design time as I can not get the syntax to compile. So, it's not the actual error I can copy.

Right now I am so confused with this syntax that I don't know how to complete this beginning:

var invoicesList =  (from  invoices in _dbSet.Where(x => x.Account == accountName && x.Hidden == false)
                 from t in _siriusContext.Transact.Where(w=>w.Extension != null && w.InvoiceNo == invoices.InvoiceNo) 
                 



                              select new InvoicesList { InvoiceNo = x.InvoiceNo, Account = x.Account, Hidden = x.Hidden, Descrip = x.Descrip1, Finalized = x.Finalized, Created = x.DateTime, Balance=}))

So, from the very top 2 lines I don't know how to get to my very last line to produce the list I need where Balance is the sum. Extension field is not nullable. I guess the original T-SQL query used isnull as the invoices not necessary have transactions.