The form is probably not submitted, is submitted to a different action page or has method type 'get'. To test, temporarily replace
<cfif isDefined("form.lstMylst")>
hello
</cfif>
with
<cfif isDefined("url.lstMylst")>
hello
</cfif>
<cfdump var="#url#" label="URL scope">
<cfdump var="#form#" label="Form scope">
Do you see 'hello'? Are the URL or form variables dumped?