This Update doesn't work ... Why?

I've done an update with this structure (I'll try to make it simple):

Update T1 set (a, b, c) =
Select ... from

   (Select x, y, complex_func(z) "J" from T2 where T2.r = T1.r) alias_t2,

   T3
   Where T3.... = alias_t2.J and T3.... = T1.... etc, etc.   )
Where T1....

This is inside a packaged procedure. It compiles ok, but when I execute, I get a ORA-904 about the T1.r column.

Why is it not visible T1 from the T2 subquery?

Thanks.

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Julio César Glez Suarez
Xixón, Asturies, Spain
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