graphml generate from my application cannot open on yEd Graph Editor

I generate graphml file from my application writing in Delphi7. Every thing is fine except when I open some my graphml file using yEd Graph Editor It raise Error like this.

test.graphml. at B.A.A.I.A.ā(Unknown Source) at B.A.A.I.D.ā(Unknown Source) at B.A.A.I.D.ă(Unknown Source) at B.A.A.B$4.run(Unknown Source) at B.A.A.U.Ċ(Unknown Source) at B.A.A.U$1.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Caused by: D.H.B.B.a: IOException :Invalid byte 1 of 1-byte UTF-8 sequence. at D.H.B.B._.ā(Unknown Source) at D.H.B.A$13.ā(Unknown Source) at D.H.B.A.ā(Unknown Source) at D.H.B.A.ā(Unknown Source) at D.H.S.ā(Unknown Source) at B.A.A.I.A.A.ā(Unknown Source) at B.A.A.B.I.O.Ă(Unknown Source) at B.A.A.B.I.O.ā(Unknown Source) at B.A.A.O.E.ā(Unknown Source) ... 7 more Caused by: com.sun.org.apache.xerces.internal.impl.io.MalformedByteSequenceException: Invalid byte 1 of 1-byte UTF-8 sequence. at com.sun.org.apache.xerces.internal.impl.io.UTF8Reader.invalidByte(Unknown Source) at com.sun.org.apache.xerces.internal.impl.io.UTF8Reader.read(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.load(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.peekChar(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(Unknown Source) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(Unknown Source) at javax.xml.parsers.DocumentBuilder.parse(Unknown Source) ... 16 more 

How I solved this problem? Thank you in advance.