Slinger SSI problems

I’m trying to use SSI in slinger. Most of the SSI commands I can get to work
fine, but the #if command doesn’t seem to work as documented. For example:

results in say being displayed. However if I do the command

the nothing appears on the web page but

does print out the text.

I also cannot work out how to reference the value of a form field. Whenever
I #echo the name of a form field nothing comes out.

Has anyone successfully used these SSI commands? If so can you give me some
examples of #if that work and examples of a form definition and an SSI
commands that access the form data.

Thanks in advance