<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ns1="http://www.marketo.com/mktows/"><SOAP-ENV:Header><ns1:AuthenticationHeader><mktowsUserId>completesolar1_70493473515C4EE90C2019</mktowsUserId><requestSignature>cfcbe2135f3c49caf96e8af3dccc65b4031256ae</requestSignature><requestTimestamp>2014-08-06T14:25:53-04:00</requestTimestamp></ns1:AuthenticationHeader></SOAP-ENV:Header><SOAP-ENV:Body><ns1:paramsSyncMultipleLeads><leadRecordList><leadRecord><Id>1060045</Id><Email>c926f676-1f57-3f9f-fa83-52a8eaa340d1@none.com</Email><ForeignSysPersonId xsi:nil="true"/><ForeignSysType xsi:nil="true"/><leadAttributeList><attribute><attrName>next_meeting_c</attrName><attrType></attrType><attrValue></attrValue></attribute></leadAttributeList></leadRecord></leadRecordList><dedupEnabled xsi:nil="true"/></ns1:paramsSyncMultipleLeads></SOAP-ENV:Body></SOAP-ENV:Envelope>
Unfortunately, we can not do that. Even if it's a single space, we would set the it to be current timestamp instead of empty value. The single space only worked for string values.
Can you help me understand what you are trying to achieve by setting the datetime value to null?