Hi!
I tried your variables in one of my images.
variables: {iptcdow}, {iptcmonthnameap} {iptcday}, {tyr4}
result: Friday, June 29, 2012
This is done post-ingest
I gave it a try on a virtual Windows system, too.
During ingest it works also.
As the only date-related variable returned is {tyr4} (what is the year of today, what is the output of the variable {iptcyear4} on your end?
Open up the IPTC-Data, paste the variable and option-klick "OK" to get the variable evaluated without saving.
Sven