About unicode

hi
First of all, I like this code, It is very good stuff.
But now I got a problem . I need you help.
I use visual studio 2003 ,I create a VC MFC project , test tidy.
I set project property "Charset" to "multibyte" everything is OK.
when I set project property "Charset" to "unicode", compile error.

My code is like that:

CString fpConfig; // this is init parameter path .
rc=tidyLoadConfig(tDoc,fpConfig );
if (rc == -1)AfxMessageBox(_T("load config error"));
compile error,the problem is tidy use "tcmbstr",and can't tansfer CString to tcmbstr.

So , I try this :
CString fp;
tcmbstr fpConfig;
fp is the real file path, can get from edit control.
fpConfig=(tcmbstr)fp.AllocSysString();
yes,this time comile OK, but run error, error msg: can't open "".

I don't know what tcmbstr is , and how to transfer CString to tcmbstr 
in "unicode" compile envirnment .

thank you a lot!!