Where condition on time travel column view

Hi,

I want to put a where condition to get the very first fresh records inserted

SELECT key,value,"value1", "$validfrom$", "$validto$" from "practice_history1" ('REQUEST_FLAGS'='ALLROWS') where "$validto$"  is null

But im getting SAP DBTech JDBC: [2048]: column store error: search table error:  [1999] Error during optimizer search  issue.

Requesting for help

Thanks in Advance,

Athrey