SOS eventTime apparently not working

[Charlton Purvis]

Hi, all:

The following long URL should not return any hits since there is no record
in our db that falls between the eventTime range I specify as part of the
URL.

http://sos-web.tamu.edu/sos-cgi/madis?service=sos&request=GetObservation&ver
sion=0.1.2&offering=ndbc_44029&responseFormat=text/xml;%20subtype=om/0.14.7&
observedProperty=http://marinemetadata.org/cf%23air_pressure_at_sea_level&ev
entTime=<gml:TimePeriod><gml:beginPosition>1990-01-01</gml:beginPosition><gm
l:endPosition>1990-02-01</gml:endPosition></gml:TimePeriod>

There is always only 1 row that should be returned -- the most recent
observation.  As of right now, the time is <time>2007-07-12
07:04:00-05</time> which isn't anywhere near the TimePeriods defined in the
query URL.

Am I doing something wrong -- that is likely!

      "sos_timeitem"             "m_date"
      "sos_offering_timeextent"  "20070530T1800Z"

It appears that I'm registering the time column properly since it does show
up in the XML.

MapServer version 4.99

TIA!

Charlton