I want to concatena two BLOB fields in a stored procedure, but I only get the first one.

select substring(OBS from 1 for 25000)
from COSTUMERS where ID = :FIRST
into :OBS_FIRST;

select substring(OBS from 1 for 25000)
from COSTUMERS where ID = :SECOND
into :OBS_SECOND;

update COSTUMERS set FIELD = coalesce(:OBS_FIRST,'') || coalesce(:OBST_SECOND,'')
where ID = :THIRD

I don't understand it. I have done the exact same thing other times. ¿ Where can be the problem ?

I know for sure they are content in both records, and I can retrieve it separately, but when I try concatenate it, I only get the :OBS_FIRST string.

Thank you.