You don't have a card for the customer who requested the activity
Before you can record activity slips for a customer, you must create a card for the customer. If you're entering an activity slip for a new customer who doesn't have a card yet, you can quickly create one using MYOB Accounting Plus's Easy-Add feature. Follow the steps in To enter information about a new customer (Easy-Add). Easy-Add enables you to create a card with only the customer's name and the standard default information that is provided for new customers. You can use the Card Information window to add contact information and make other changes later on if you like. (Adding cards)