maybe this workaround helps you:
Dim intHandleNew, strTextNew, intErrorNew
Dim intHandleOld, strMyTextOld, intErrorOld
intHandleNew = TextFileOpen("c:\test.asc",tfCreate)
intTextNew= TextfileWriteLn(intHandleNew,"1 first line")
intTextNew= TextfileWriteLn(intHandleNew,"2 second line")
intErrorNew = TextFileClose(intHandleNew)
Call FileCopy("c:\test.asc","c:\test.old")
intHandleNew = TextFileOpen("c:\test.asc",tfCreate)
intTextNew= TextfileWriteLn(intHandleNew,"new Line")
intHandleOld = TextFileOpen("c:\test.old",tfRead)
Do While Not TextFileEOF(intHandleOld)
strTextNew = TextFileReadLn(intHandleOld)
intTextNew= TextfileWriteLn(intHandleNew,strTextNew)
loop
intErrorNew = TextFileClose(intHandleNew)
intErrorOld = TextFileClose(intHandleOld)
call FileDelete("c:\test.old", 1)
Andreas