Testing GPE synchronisation, using the SVN 0.3x source, I get the following errors appearing during the sync:
element Until: Schemas validity error : Element 'Until': This element is not expected. Expected is ( Frequency ).
element Count: Schemas validity error : Element 'Count': This element is not expected. Expected is ( Frequency ).
element Until: Schemas validity error : Element 'Until': This element is not expected. Expected is ( Frequency ).
The log file shows that there are two records which contain <Until>. Here is the relevant part of one of them:
<RecurrenceRule>
<Frequency>YEARLY</Frequency>
<Until>20301231</Until>
<Interval>1</Interval>
</RecurrenceRule>
There are several which contain <Count>. I did note that only one of them also contains <Frequency>YEARLY, although I can't be sure this is the one causing the error:
<RecurrenceRule>
<Frequency>YEARLY</Frequency>
<Count>0</Count>
<Interval>1</Interval>
</RecurrenceRule>
Note that gpe-sync does not provide any schemas of its own.