Performance Tuning :: Oracle Database 10g Enterprise Edition 10.2.0.4.0 - 64bi

I am querying v$sga and getting variable size : 211337216 bytes.when querying v$sgastat then getting

java Pool : 16777216
Large Pool : 41943040
Shared pool : 398560392

But as per my knowledge following condition should satisfy,but not getting

[code]

Variable sga = java pool + large pool + shared pool
select pool,name,sum(bytes)
from v$sgastat
where pool in ('shared pool','java pool','large pool')
group by pool,name;

Here variable size using v$sga : 211337216 bytes

and java pool + large pool + shared pool : 211302536 bytes.

[/code]
but it should match?