FB 1.5.1

When I exequte this SQL command, the result is OK:

select A.*,
(select BBBBData from GET_From_BBBB(A.ID1, A.ID2)) as Bdata
from AAAA A

I see Bdata column too in the result dataset;)

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When I add an order tag, I get an error message:

select A.*,
(select BBBBData from GET_From_BBBB(A.ID1, A.ID2)) as Bdata
from AAAA A
order by Bdata

>>>

Dynamic SQL Error
SQL error code = -206
Column unknown
Bdata

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Is it an error or I do something wrong?

When I get data from BBBB table (against GET_From_BBBB sp) the return
column good.

eMeL