Where is your NSQL?
If you're using (for example) any to_date() / to_char() methods around this construct for your date parameter, most likely in order to run the same non-NSQL version of the query in another query editor outside Clarity, then the date format expectations will be different.
Normally in Clarity NSQL portlets you do not need to use those conversion functions.
Also I would expect that YYYY-MM-DD"T"HH:MI:SS is the wrong format to use for the incoming data to an NSQL parameter, and YYYY-MM-DD HH24:MI:SS is expected instead.