Syntax Error

Hi guys..

When I try and run the following code it says that there is a missing
operator..

SELECT
curr.portfolio_code,
curr.date,
(curr.gross_index-mo1.gross_index)/mo1.gross_index AS 1MONTH_RETURN,
(curr.gross_index-mo1.gross_index)/mo1.gross_index AS 3MONTH_RETURN
FROM portfolio_performance AS curr
LEFT OUTER JOIN portfolio_performance AS mo1
ON curr.date =
dateserial(year(dateadd('d',-1,dateserial(Year([mo1].date),
MONTH([mo1].date)+2, 1))),
month(dateadd('d',-1,dateserial(Year([mo1].date), MONTH([mo1].date)+2,
1))),day(dateadd('d',-1,dateserial(Year([mo1].date),MONTH([mo1].date)+2,
1))))
LEFT OUTER JOIN portfolio_performance AS mo3
ON curr.date =
dateserial(year(dateadd('d',-1,dateserial(Year([mo3].date),
MONTH([mo3].date)+4, 1))),
month(dateadd('d',-1,dateserial(Year([mo3].date), MONTH([mo3].date)+4,
1))),day(dateadd('d',-1,dateserial(Year([mo3].date),MONTH([mo3].date)+4,
1))))
;

However, when I run the same code, minus the second left outer join it
works perfectly..

SELECT
curr.portfolio_code,
curr.date,
(curr.gross_index-mo1.gross_index)/mo1.gross_index AS 1MONTH_RETURN
FROM portfolio_performance AS curr
LEFT OUTER JOIN portfolio_performance AS mo1
ON curr.date =
dateserial(year(dateadd('d',-1,dateserial(Year([mo1].date),
MONTH([mo1].date)+2, 1))),
month(dateadd('d',-1,dateserial(Year([mo1].date), MONTH([mo1].date)+2,
1))),day(dateadd('d',-1,dateserial(Year([mo1].date),MONTH([mo1].date)+2,
1))));

Any help would be appreciated.. im sure its only something minor!