Normal text strings are always of type char*.

Some compilers will default char to signed char. Some to unsigned char.
In your case, your array is declared as an array of pointers to unsigned char, while the compiler is defaulting to signed char.

Either check for compiler switches to change the default to unsigned char (bad choice) or write your code so it can handle either alternative. In this case, the array should not use the unsigned keyword. Instead, you should typecast to unsigned char when assigning to SBUF.