the stranges symbolset file parsing error when using mapscript: loadSymbolSet(): Unknown identifier. Parsing error near (SYMBOL):(line 0)

[Dolf Andringa]

Hi people,

I am having the strangest problem. When setting a symbolsetfile to a 
mapObj with mapscript in python, and in the same script creating a 
classObj with an expression, I get an error: mapscript.MapServerError: 
loadSymbolSet(): Unknown identifier. Parsing error
I limited the error down to a small testscrip which is below. If I 
remove eiter one of the last two lines in the script, the error 
disappears. In the original script also layers and stuff (connection 
through ogr to postgres/postgis) are added, but that makes no 
difference. I also included my symbols file (see below). I added a BOF 
and EOF below to show the beginning and ends of the files, of course 
they are not in the actual files. The full traceback of the python error 
can be seen below as well. I am running Python 2.4.4 on Debian Sarge 
with a self compiled version of mapserver 4.10.0, gdal 1.3.2 and proj 4.5.0.
I have no idea what the problem is. I hope anybody can help.
Thanks,

Dolf.

testscript.py:

BOF
import mapscript
mapobj=mapscript.mapObj()
outputFormat=mapscript.outputFormatObj("GD/PNG")
outputFormat.name="png24"
outputFormat.setMimetype("image/png")
outputFormat.imagemode=1
outputFormat.setExtension("png")
mapobj.legend.status=1
mapobj.legend.keysizex=100
mapobj.legend.keysizey=30
mapobj.legend.keyspacingy=20
mapobj.legend.width=100
mapobj.setSize(600,1200)
mapobj.setExtent(132771,447652,134477,451064)
mapobj.setOutputFormat(outputFormat)
style=mapscript.styleObj()
style.symbolname="point5"
style.color=mapscript.colorObj(225,0,0)
cls=mapscript.classObj()
cls.insertStyle(style)
cls.name="testclass"
cls.setExpression("(4 + 4)")
mapobj.setSymbolSet('test_symbols.set')
EOF

test_symbols.set file:

BOF
SYMBOL
   NAME "point5"
   TYPE ELLIPSE
   FILLED true
   POINTS
     5 5
   END
END
EOF

Python error:

Traceback (most recent call last):
   File "testscript.py", line 39, in ?
     mapobj.setSymbolSet('test_symbols.set')
   File "/usr/lib/python2.4/site-packages/mapscript.py", line 1382, in 
setSymbolSet
     def setSymbolSet(*args): return _mapscript.mapObj_setSymbolSet(*args)
_mapscript.MapServerError: loadSymbolSet(): Unknown identifier. Parsing 
error near (SYMBOL):(line 0)