VISIO SolutionXML. Not retaining CDATA blocks?

[LesEnstone]

I'm trying to store data inside Visio.VDX files, in various SolutionXML
blocks.
It works OK except for [CDATA[ blocks.
Visio seems to save the .VDX file back out without these tages around the
data.

Has anybody found this problems and got a work round ?
Is there an attribute I need to set in the XML ? ......?

Thanks in anticipation
Les