Using DOM in XSLT java extension throws exception

Hi,

I try to use DOM within a java extension called by an XSLT mapping in PI 7.11. I use the following code:

InputStream inputStream;
[...]
javax.xml.parsers.DocumentBuilder docBuilder = javax.xml.parsers.DocumentBuilderFactory.newInstance().newDocumentBuilder();
org.w3c.dom.DocumentDocument document = docBuilder.parse(inputStream);

But during the mapping I get the following exception:

Error occured in bean SMPP_CALL_JAVA_RUNTIME3.
Thrown:
javax.xml.parsers.FactoryConfigurationError: Provider com.sap.aii.ib.server.mapping.execution.jaxpfactories.MappingDocumentBuilderFactory not found
at javax.xml.parsers.DocumentBuilderFactory.newInstance(DocumentBuilderFactory.java:114)

Can anybody help with this issue?

Thanks in advance!

Hans