imagemap outputformat definition with php-mapscript fails

[patrick.luley@…]

The outputformat "imagemap" does not produce a working output, if the the
outputformat is defined with php-mapscript.
example outputformat defnition...
	$Map->outputformat->set("name","imagemap");
	$Map->outputformat->set("mimetype", "text/html"); 
	$Map->outputformat->set("driver", "imagemap"); 
	$Map->outputformat->set("extension", "html"); 
	$Map->outputformat->setOption("formatoption", "MAPNAME=poi");
	$Map->outputformat->setOption("formatoption",           
"polyhref=showPoiInfo_Web.php?langkey=1&poiID=%s");

As result a HTML file is generated with a MAP-tag inside, but between the MAP
tags there are only some ASCII characters - looks like binery data. The map-name
is also not set. the generated imagemap looks like this...

<map name="(null)" width="550" height="450"> „ÊI&</map>

This behaviour was reproduced by some colleagues on other installations :(