validating an XML file against a DTD

I have a problem!

I am unable to validate the xml against DTD. when I am setting the validation feature as true.if i modify the Xml file which violates the DTD , the modification should not effect the current XML, but when I am saving XML using a transformer. The Xml is saving with modification which violates the DTD

please help to solve this problem

Thanks,

shiva

[397 byte] By [sshivaa] at [2007-10-2 8:41:30]