TBuf & TPtrC ???

How can I assign the content of TPtrC to TBuf, not for initialization??

I tried:

TBuf<50> buf1;
....
TLex lex(aLine);
lex.Mark();
while(!lex.Eos())
{
.....
buf1.Copy(lex.MarkedToken()); //I can not get the content pointed by lex.MarkToken()
}
.....


Expert, can you help???

Thanks!!!