[PD] Strange problem with vline~

[Carlos Pita]

[ bang ( ------[ 0 0 0, 1 15 0 (
   |              |
   |           [ vline~ ]
   |              |
   ------------[ tabwrite~ t ]

I have this simple patch above with
a [bang( which triggers a couple
of messages describing a line
segment ranging from 0 to 1 in 15 ms,
and at the same time the writing
of this segment into table t.
Suppose a typical setting with
sample rate=44100, table size=1024.
If block size is small enough (~64 or
less) the patch works ok. But with
bigger block sizes the segment
appears displaced to the right of
the table left border as
if its starting time was out of
sync. Stranger yet, cause it
starts in different positions
of the table every time I press
the [bang(. As I increment
block size the average offset
increases too. Is this a expected
behaviour of [vline~]? Am I making
some mistake? I understand that
[vline] schedules its segments
at "audio time", in other words
that it has sample-precision
instead of block-precision.
Thank you in advance.
Regards,
Carlos