From Xojo Documentation
Call the method pointed by the delegate. You must pass the same parameters as the method's ones and, if the method returns a value, you must use the return value as well.
If you defined a delegate as:
then you must use Invoke with the same parameters' type, as in:
// <— Set d as your code requires
d.Invoke(1, 10, "An example string") // Values are indicative
By contrast, if the Delegate is set to return a value as in:
then you must use the value returned by Invoke, as in: