eConnect SOP Return behaviour

Hi,

If I execute this code eConnect gives no error messages, not does it create any data, any ideas?

declare @p4 nvarchar(20)

set @p4=N'RET000016as'

declare @p8 int

set @p8=0

declare @p9 nvarchar(1)

set @p9=N''

exec taSopLineIvcInsert @I_vSOPTYPE=4,@I_vSOPNUMBE=@p4,@I_vCUSTNMBR=N'0186',@I_vDOCDATE='2013-07-23 00:00:00',@I_vITEMNMBR=N'HG-910',@I_vQUANTITY=1,@I_vQTYONHND=1,@O_iErrorState=@p8 output,@oErrString=@p9 output,@I_vUNITPRCE=1110,@I_vXTNDPRCE=1110

select @p8, @p9

SELECT *

FROM SOP10100

WHERE SOPNUMBE = 'RET000016as'