Try the following syntax instead:
SET vSetNumber = 3; LOAD Field AS "ER01_Set$(vSetNumber)_ID", // will do Field AS [ER01_Set$(vSetNumber)_ID2] // will do as well INLINE [ Field AAAA BBBB CCCC ];
Although I'm loading from an INLINE table, the renaming will work from any source as well. Usually, field names with blanks or non ASCII characters require to be enclosed by double quotes or square brackets. The $() will make the variable to be expanded within the field name.
Hope that helps.