You didn't specify the field name in the textbox value assigment.
BTW, You don't need to compare result of 'Cdm30wrk.wrk_stat = "A-ACCTNG"' to the .t. because it's already logical value. There's also no need to ALLTRIM(Cdm30wrk.cmp_name) because foxpro compares the string on the left to the lenght of the string on the right.

SELECT SUM(Cdm30wrk.wrk_tlamt) AS LastYearSales;
 FROM  classicdb!cdm30wrk;
 WHERE Cdm30wrk.wrk_stat = "A-ACCTNG" ;
   AND Cdm30wrk.wrk_page = 1;
   AND Cdm30wrk.cmp_name = lcThisClient;
   AND YEAR(Cdm30wrk.date_updt) = ldLastYear;
into cursor curLastYearSales
thisform.pgfClientDetails.pagAccountDetails.txtLastYearSales.value = curLastYearSales.LastYearSales

>Please show me why this code returns what it does.
>

>local ldLastYear, lcThisClient, curLastYearSales
>
>***
>
>ldLastYear = YEAR(DATE()) - 1
>lcThisClient = thisform.cboClientName.Value
>
>
>SELECT SUM(Cdm30wrk.wrk_tlamt);
> FROM  classicdb!cdm30wrk;
> WHERE Cdm30wrk.wrk_stat = "A-ACCTNG" = .T.;
>   AND Cdm30wrk.wrk_page = 1;
>   AND ALLT(Cdm30wrk.cmp_name) = lcThisClient;
>   AND YEAR(Cdm30wrk.date_updt) = ldLastYear;
>into cursor curLastYearSales
>thisform.pgfClientDetails.pagAccountDetails.txtLastYearSales.value = curLastYearSales
>

>This code is in the init of the form. Optimistic locking, table buffered private data session.
>Instead of a currency amount I get F for any client I select on the form. I put a thisform.refresh in the LostFocus of the combo that selects the client to view.
>
>I tested the query (without form related variables) in the command window with a hard coded client selection and the query returned 1 record, a nice numerical amount. What is different? Is the Init the wrong place to place the code? Have I done something wacky with the assignments?
>
>Regards and TIA,
>Matthew