loc backcourse approach

hello,
am i wrong or it is the software or MSFS ?
Using the b737, I did try to land at CYHZ (halifax canada) with LNAV engaged and LOC32 approach select and it did work well.
but if i try to ``handfly it using the mcp (not in LNAV/Vnav) and select the APP mode, the LOC frequency it is simply not working. In the MSFS programm the localiser is only for rNWAY 15 ?
BY handfly i mean: AT on, speed mod, heading select appropirate to intercept the course, APP armed AP cmd1 engaged.
Any ideas
jean-louis