Error Number = 2221 Stored Procedure= taSopLineIvcInsert Error Description = Duplicate document number. If adding or updating lines to an existing document, UpdateIfExists must = 1

i am using Microsoft Dyanmic Gp, econnect 10.0. i am trying get the tasoplineinvoiceitems. 

If i set for updateifexist =0; then it gives the error like:

eConnectTraceSource Error: 735 : Create Transaction Entity produced the following exception:Sql procedure error codes returned:Error Number = 2221  Stored Procedure= taSopLineIvcInsert  Error Description = Duplicate document number. If adding or updating lines to an existing document, UpdateIfExists must = 1

Node Identifier Parameters: taSopLineIvcInsert

SOPNUMBE =   220,584

SOPTYPE = 3

LNITMSEQ = 3

Related Error Code Parameters for Node : taSopLineIvcInsert

UpdateIfExists = Note: This parameter was not passed in, no value for the parameter will be returned.

<taSopLineIvcInsert>

  <SOPTYPE>3</SOPTYPE>

  <SOPNUMBE>  220,584</SOPNUMBE>

  <CUSTNMBR>3253</CUSTNMBR>

  <DOCDATE>4/08/2011</DOCDATE>

  <ITEMNMBR>4410 - BA - 001</ITEMNMBR>

  <UNITPRCE>162.79</UNITPRCE>

  <XTNDPRCE>162.79</XTNDPRCE>

  <QUANTITY>1</QUANTITY>

  <ITEMDESC>Standard Designer Rpl DH</ITEMDESC>

  <NONINVEN>1</NONINVEN>

  <LNITMSEQ>3</LNITMSEQ>

  <DOCID>STDINV</DOCID>

  <DEFEXTPRICE>1</DEFEXTPRICE>

  <UOFM>EACH</UOFM>

</taSopLineIvcInsert>

...................................................................................................................................................................................

Note:Even i try  to set 1 for updateifExist

 i chenged value of updateifexist=1;

 i got error like :eConnectTraceSource Error: 735 : Create Transaction Entity produced the following exception: Sql procedure error codes returned: 

Error Number = 2608  Stored Procedure= taSopLineIvcInsert  Error Description = Document does not exist in the Work File - SOP10100 - the Line can not be modifiedNode Identifier Parameters: taSopLineIvcInsert

SOPNUMBE =   220,584

SOPTYPE = 3

LNITMSEQ = 2

Related Error Code Parameters for Node : taSopLineIvcInsert

UpdateIfExists = 1

Can you please give the suggestion, where i did mistake here and how much value i have to set for the upadateifexist fpr tasoplineiveinsert.