oracle want add 1 extent of 2052 blocks
if blocksize is 4 k => 8M
8M are not disponible on the tablespace,

you can alter the size of next extent
alter table ... storage (next extents 2M) for example

you can see the biggest extent disponible on your tablespace
select max(bytes) from dba_free_space
where tablespace_name= ...

and adjust the next on consequence

it's preferable to fix the pctincrease at 0 and define the initial
extent at the good dimension and the next at 10% of the initial

and other solution after this is to add datafile to tablespace

i hope have respond to your problem

sorry for my english

if you want more information you can mail me monday
at [email protected]
for this week is my mail
after [email protected]

salutations
bertrand