Ignore bins

Hello!
Why can I not use ignore bin to default values?

In reply to Shashank Gurijala:

Can you elaborate ?

In reply to Rahulkumar:

illegal_bins a2 []  =   default//fine
ignore_bins a2 []   =   default//error

In reply to Shashank Gurijala:
Dave have answered hereā€¦
https://verificationacademy.com/forums/coverage/how-ignore-default-clause-covergroup