I have set my page to Security as follows

and am trying to pull in a checksum and URL to add to my deep link value, but the following does not return a checksum ? Waht am I doing wrong. I tried all the variations of p_checksum_type and I tried removing it.
select APEX_UTIL.PREPARE_URL(p_url =>'f?p=100:14:::NO::P14_PARAM1,P14_PARAM1:DSRA,111', p_checksum_type => SESSION) as url from dual;
URL
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f?p=100:14:::NO::P14_PARAM1,P14_PARAM1:DSRA,111