Thank you for reaching out to the community!
I'm sorry to hear that you are unable to send an email to your first 100 contacts. This is usually a simple issue that is easily resolved. Would you be able to provide us with the error message that you are receiving when trying to schedule? Sometimes there are banners at the top of your account (usually in green or yellow) that will explain what may be preventing you from sending.
We will be looking forward to your reply.