Also, there are a number of issues with that subroutine:
1. Specifying an entity on the left side of an Exp statement does not work. You can only write to the entity that is being calculated. In this case this rule is only allowed to run on entity '1500' so it will only write data to the entity. When data is needed from another entity and there is not parent-child relationship between them then the Sub Allocate should be used.
2. You specify a single data value, vT3Rcl, on the right side of your Exp statement but you are not specifying any of the custom dimensions on the left side which means that rule will populate every valid member of every custom dimension with that data value for the accounts you specify. This is called a data explosion. You may be alright if the CustomTopMembers of those accounts are blank or specify [None] but if that is every changed this rule will cause an issue.