You have used all of the slots for a particular slot type. There are several ways to address this issue; steps to address this issue should be:
Slot Conversion: Convert the slots of your program to create an available slot.
Use a Refill Slot: If all of your slots or utilized, then you can use refill slots to enroll the member. You may need to convert your refill slots to create an available desired slot type.
Amend the Grant: An amendment request can be created through eGrants.
See also: