The maximum associations of the device are been reached. No more associations are possible.
The Application Program of a device with Mask Version 2.5 allows the manufacturer to instantiate up to 247 Group Objects, which means in that case that 247 of the possible 250 associations are already reserved for the sending associations of these Group Objects. So only 3 additional receiving associations are in this case guaranteed to succeed.
What to do?
Remove the additional receiving associations in order to be able to link more Group Addresses and if this does not help you, or not possible get in contact with the manufacturer, as you might need another application.