@GURUPRASAD MADAPURA VENKATESHAIAH​, I've had that error before. Trying to remember the cause....

I'll try to remember. In the mean time, here is a notebook I have that is very similar and works for me. If you try building yours up, step by step, using this as a template, hopefully that will do it. Obviously, you don't need the json explosion parts or the where clause. That's just to handle some messiness in the data I am processing.

CREATE OR REFRESH STREAMING LIVE TABLE currStudents_ingest
AS SELECT
  col.*
  ,file_modification_time
FROM  (
SELECT fi.file_modification_time, EXPLODE_OUTER (fi.students)
FROM STREAM(LIVE.currStudents_streamFiles) AS fi 
)
WHERE col.id IS NOT NULL
;
 
CREATE OR REFRESH STREAMING LIVE TABLE currStudents_SCD;
 
APPLY CHANGES INTO
  live.currStudents_SCD
FROM
  stream(live.currStudents_ingest)
KEYS
  (id)
SEQUENCE BY
  file_modification_time
STORED AS
  SCD TYPE 2
TRACK HISTORY ON * EXCEPT (file_modification_time)
;