Hi Irena,
In 11g @ character is not allow as per password policy.
You need to enter a master password without @ character.
When sapinst is trying to change the password of SAPSR3 schema with the master password which in turn having a @ character , it won't allow the brconnect to do that as it is not supported by 11g.
It was possible in 10g though.
This will resolve your error.
With Regards
Ashutosh Chaturvedi