how to put any one of 0~255 digit num into a string(1 by(編號:843)

Here is my question as follow and I'll be much appricated if anyone could help me solve the problem.
我試著將 0 ~255 數字(integer) 存入一 string, 每個數字佔一個 byte 的長度; 程式片段如下:
For i = 0 To (compLen -1) ' 迴圈執行 次。
     CompStr = CompStr & Chr$(bytearray(i))
     Next i

0~ 128 皆 OK!, 但 129 ~254 則不 WORK
/* Notes: compStr is a string, bytearray is a array of Byte */
測試方法如下:
     Function     result  
---------------------------------------------------
Asc(Chr(0)) ----> 0
     Asc(Chr(1)) ----> 1
       ...   
     Asc(Chr(128)) ----> 128 
    /* not working begin */
     Asc(Chr(129)) ----> 0 /* not working */
       ...
     Asc(Chr(254)) ----> 0/* not working */
     /* not working end */
     Asc(Chr(255)) ----> 255/* working */
請問: How to solve the problem or somthing wrong with the program code ?