The Size of an Array Must Be a Constant or a Number
From Xojo Documentation
Error message
When you declare and size an array using a Dim statement, the size of the array must be indicated by either a constant or a number.
Notes
If you need a variable length array, declare the array as having no bounds and then use the Append method to add elements, such as:
Examples
Trying to size an array using a variable:
See Also
Dim statement.