BLOCK statement and CONFIGURATION

[andy]

I am coding an architecture wth a block statement

ARCHITERCURE struct OF myent IS

....

BEGIN
...
b1: BLOCK IS

i_comp1: conmp1
PORT MAP (....)
BEGIN

END;

END struct;

and I cannot conmpile such

CONFIGURATION myent_struct_conf OF myent
FOR i_comp1: comp1
USE CONFIGURATION work.comp1_conf
END FOR;
END CONFIGURATION;

It seems I am doing worng when accessing components which are
istantiated inside blocks ...
I also tried unsuccessfully something like
b1. FOR i_comp1: comp1

thanks in advance