Curious XML Validation issue.

["Wadsworth, Geoffrey" <GWadsworth@thedoctors.com>]

I have defined a schema for an import business document. The process that is
producing the xml that the schema is validating is producing a useable xml
document. It does not validate because the some of the nodes are in a
different order.
Example: 
		<PAY_PLAN>
			<INSTALLMENT>
				<INSTALLMENT_NUM>1</INSTALLMENT_NUM>
				<INSTALLMENT_DESCR>1 of
4</INSTALLMENT_DESCR>
				<DUE_DATE>12/28/02</DUE_DATE>
				<PREMIUM_AMT/>
				<PAST_DUE_AMT/>
				<TOTAL_AMT/>
			</INSTALLMENT>
			<PAY_PLAN_TYPE_CODE>CUSTOM</PAY_PLAN_TYPE_CODE>
			<REMITTANCE_DESCR>1 of 4</REMITTANCE_DESCR>
			<NUM_OF_PAYMENTS_QTY>1 of 4</NUM_OF_PAYMENTS_QTY>
			<PLAN_PREMIUM_AMT/>
			<PLAN_PAST_DUE_AMT/>
			<PLAN_TOTAL_AMT/>
		</PAY_PLAN>
The above is what is being sent. The schema complains because the
<PAY_PLAN_TYPE_CODE> & <REMITTANCE_DESCR> nodes are defined as being before
the <INSTALLMENT> node. This puzzles me because the order of the nodes under
doesn't matter when I am accessing the data but the schema complains anyway.
I am doing the validation in VB using MSXML4. Is there a way for the schema
to ignore the order? I would also be curious as to why the schema even cares
about the order. 

Thanks, 
Geoff