Can someone help me figure out why the following update statement is not fully optimized? Thanks!

*** sys(3054) tells me that it is using the curaccount.cchanged index, and the curaccount. xline index,
**but it doesn't say it is using the account clineid index, and it says the optimization for table account is none.
*-- as a result I had to abandon this code and replace it with the seek/looping code below it
*** I have numerous updates statements of the exact same form, they all run slow, haven't tested them all yet.




*-- there is an index on account.clineid called clineid
*-- there is an index on curaccount.clineid called xline
*-- there is an index on curaccount.cchanged called xchange

SET ENGINEBEHAVIOR 80 && tried with and without this
PUBLIC cmemvar
=SYS(3054,11,"cmemvar")
UPDATE account SET cacc = curaccount.cacc, cid = curaccount.cid from account join curaccount on account.clineid = curaccount.clineid where curaccount.cchanged='Y'
?cmemvar

*--- replacement code because can't get the above update statement optimized.
Set Order To xchange In curaccount
Go Top In curaccount
If Seek("Y","curaccount","xchange")
Do While Not Eof("curaccount") And curaccount.cchanged="Y"
If Seek("curaccount.clineid","account","clineid")
Replace cacc With curaccount.cacc, cid With curaccount.cid In account
Endif
Skip In curaccount
Enddo
Endif