Sending notification email to a group which is under a local domain

Hi,

I can assign tasks to local groups (under local domain, but people are from enterprise). But i cannot send email to these local groups. Send mail operation accepts only email address as input. Could you advice an easy way to do it. I tried FindGroupMembers operation, but it gives the error 'String length is wrong'.
I use LC 8.2

Thanks in advance
Sedat,