Me too facing same issue. Generally ACCOUNT_INACTIVE comes when billing information is not set, but I've set billing info on both MCC test account and the child account. I've tried unlinking and linking them back again. My test mcc account is not yet approved.
here is my soap request.
[Aug 29 2013 11:07:37.000000 - ERROR] POST /api/adwords/cm/v201306/CampaignService?access_token=ya29.*****************4Lf0d*******RTeg************ZRgjvz0rz HTTP/1.1
Host:
adwords.google.comConnection: Keep-Alive
User-Agent: PHP-SOAP/5.4.14, gzip
Accept-Encoding: gzip, deflate
Content-Encoding: gzip
Content-Type: text/xml; charset=utf-8
SOAPAction: ""
Content-Length: 521
<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="
http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1="
https://adwords.google.com/api/adwords/cm/v201306">
<SOAP-ENV:Header>
<ns1:RequestHeader>
<ns1:clientCustomerId>511-***-6051</ns1:clientCustomerId>
<ns1:developerToken>tl7******sjZzY******s3iA</ns1:developerToken>
<ns1:userAgent>th****th sy***ms (AwApi-PHP/4.5.1, Common-PHP/5.0.0, PHP/5.4.14)</ns1:userAgent>
</ns1:RequestHeader>
</SOAP-ENV:Header>
<SOAP-ENV:Body>
<ns1:get>
<ns1:serviceSelector>
<ns1:fields>Id</ns1:fields>
<ns1:fields>Name</ns1:fields>
<ns1:fields>Impressions</ns1:fields>
<ns1:fields>Clicks</ns1:fields>
<ns1:fields>Cost</ns1:fields>
<ns1:fields>Ctr</ns1:fields>
<ns1:predicates>
<ns1:field>Impressions</ns1:field>
<ns1:operator>GREATER_THAN</ns1:operator>
<ns1:values>0</ns1:values>
</ns1:predicates>
<ns1:dateRange>
<ns1:min>20130822</ns1:min>
<ns1:max>20130828</ns1:max>
</ns1:dateRange>
<ns1:paging>
<ns1:startIndex>0</ns1:startIndex>
<ns1:numberResults>500</ns1:numberResults>
</ns1:paging>
</ns1:serviceSelector>
</ns1:get>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
AND THE RESPONSE
HTTP/1.1 500 Internal Server Error
Content-Type: text/xml; charset=UTF-8
Content-Encoding: gzip
Date: Thu, 29 Aug 2013 05:37:47 GMT
Expires: Thu, 29 Aug 2013 05:37:47 GMT
Cache-Control: private, max-age=0
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block
Content-Length: 503
Server: GSE
<?xml version="1.0"?>
<soap:Envelope xmlns:soap="
http://schemas.xmlsoap.org/soap/envelope/">
<soap:Header>
<ResponseHeader xmlns="
https://adwords.google.com/api/adwords/cm/v201306">
<requestId>0004e50f818771500a422541000031df</requestId>
<serviceName>CampaignService</serviceName>
<methodName>get</methodName>
<operations>0</operations>
<responseTime>49</responseTime>
</ResponseHeader>
</soap:Header>
<soap:Body>
<soap:Fault>
<faultcode>soap:Server</faultcode>
<faultstring>[QuotaCheckError.ACCOUNT_INACTIVE @ ; trigger:'<null>']</faultstring>
<detail>
<ApiExceptionFault xmlns="
https://adwords.google.com/api/adwords/cm/v201306">
<message>[QuotaCheckError.ACCOUNT_INACTIVE @ ; trigger:'<null>']</message>
<ApplicationException.Type>ApiException</ApplicationException.Type>
<errors xmlns:xsi="
http://www.w3.org/2001/XMLSchema-instance" xsi:type="QuotaCheckError">
<fieldPath/>
<trigger><null></trigger>
<errorString>QuotaCheckError.ACCOUNT_INACTIVE</errorString>
<ApiError.Type>QuotaCheckError</ApiError.Type>
<reason>ACCOUNT_INACTIVE</reason>
</errors>
</ApiExceptionFault>
</detail>
</soap:Fault>
</soap:Body>
</soap:Envelope>