Msg 207, Level 16, State 1, Line 25
Invalid column name 'username'.
Msg 207, Level 16, State 1, Line 25
Invalid column name 'surname'.
Msg 207, Level 16, State 1, Line 3
Invalid column name 'username'.
Msg 207, Level 16, State 1, Line 3
Invalid column name 'surname'.

select 
username + ' ' + surname,
DATENAME(MONTH, createdon) AS theMonth,
sum(CASE WHEN RowNo=1 THEN placementfee ELSE 0 END) as 'Amount Boarded', 
count(distinct placementid) 'Number of Deals'
,SUM(netsum) as 'Amount Invoiced',
SUM(CASE WHEN RowNo=1 THEN placementfee ELSE 0 END)- SUM(netsum)as 'Waiting to invoice'
FROM
(
SELECT ROW_NUMBER() OVER (PARTITION BY p.placementid ORDER BY i.invoiceid) AS RowNo,p.createdon,p.placementfee,p.placementid,i.netsum
 FROM placements p
join placementconsultants pc on pc.placementid = p.placementid 
join users u on u.userid = pc.userid 
left outer join placementinvoices pp on pp.placementid = p.placementid 
left join invoices i on i.invoiceid = pp.invoiceid

WHERE	p.createdon >= '20080101'
	AND p.createdon < '20150101'
AND p.createdon < '20150101' and p.placementtypeid  not in('6','5','17','19','23','26') 

)tmp

GROUP BY DATENAME(MONTH, tmp.createdon),
	 DATEPART(MONTH, tmp.createdon),tmp.username + ' ' + tmp.surname

ORDER BY DATEPART(MONTH, tmp.createdon)