After running my query to a #temp table I have tried this

DECLARE @Parameter varchar(12)

BEGIN

IF @Parameter = 'Credit'

THEN

(SELECT [Doc Number],[Customer Name],[Owner],[Rev Type1],[Mail Date],[Revenue Date],[Days Outstanding],[0-30 Days],[31-60 Days],

[61-90 Days],[91-120 Days],[121-150 Days],[151 + Days],[Customer ID],

[Total Outstanding],([0-30 Days]+[31-60 Days]+[61-90 Days]+[91-120 Days]+[121-150 Days]+[151 + Days]) as [Total Outstanding2],[Reference]

FROM #t1

WHERE ([0-30 Days]+[31-60 Days]+[61-90 Days]+[91-120 Days]+[121-150 Days]+[151 + Days]) < 0)

ELSE

SELECT [Doc Number],[Customer Name],[Owner],[Rev Type1],[Mail Date],[Revenue Date],[Days Outstanding],[0-30 Days],[31-60 Days],

[61-90 Days],[91-120 Days],[121-150 Days],[151 + Days],[Customer ID],

[Total Outstanding],([0-30 Days]+[31-60 Days]+[61-90 Days]+[91-120 Days]+[121-150 Days]+[151 + Days]) as [Total Outstanding2],[Reference]

FROM #t1

WHERE ([0-30 Days]+[31-60 Days]+[61-90 Days]+[91-120 Days]+[121-150 Days]+[151 + Days]) > 0

END

But I am getting "Msg 156, Level 15, State 1, Line 5

Incorrect syntax near the keyword 'THEN'.

Msg 156, Level 15, State 1, Line 14

Incorrect syntax near the keyword 'ELSE'."

Any suggestions