Oracle Database Discussions

HI all
I use ASM instance with ASM dik group , when I add datafile to tablespace :
SQL> alter tablespace INDM add datafile '+STARINS' size 50G;
alter tablespace INDM add datafile '+STARINS' size 50G
*
ERROR at line 1:
ORA-01144: File size (6553600 blocks) exceeds maximum of 4194303 blocks

I had to add datafile with max 30G , but I thought that ASM copes larger files.
we have one diskgroup +STARINS, to two ASM DISK :

Am I making any mistage by configuration ..this is may first contact with ASM and immediately serious project :)

Can You give me any recommendation ?

Thank You Brano