< Seqno > is not an item or a parameter of ...

Extremely annoying error message, occurs both in P5 and Windev itself. 

Script runs correctly once, then get this error on code like this:

dsAusWages    is Data Source 

sQuery    is string    = [

    Select

    cast(' ' as text) as ChequeNumber,

    cast(' ' as text) as PaymentDate,

    cast(' ' as text) as Name,

    cast(' ' as text) as PayCategoryName,

    cast(' ' as text) as PayCategoryType,    -- Wage, Entitlement, Super, Tax

    000000.0000 as PayHours,

    000000.0000 as PayRate,

    00000000.00 as PayAmount

    From txtTable

    Where 1=2                                            -- get structure only

]

HExecuteSQLQuery(dsAusWages,HFCS_Connection,sQuery)    // ERROR HERE 2ND TIME AROUND

Query runs OK in HFSQL control centre.

Solution - add this line after the data source is no longer required:

HCancelDeclaration(dsAusWages)

This command is said to free the resources of a query after calling HExecuteSQLQuery

Tested so far on a script with only one data source.