object helpfiles are useful here; send the [buffer~] a read message (read myfile.wav, for example) then use loadbang, or use a [loadmess myfile.wav] and [prepend read].

Have a look at the Max window when you click the [read sampleA2.wav] message, does it say "cannot find…" or something? Max needs to know where your files are stored (you set this in File Preferences). I’m not in front of max right now, but you can preload a sample into buffer on patch startup; open the helpfile for buffer and search in there, my message syntax may be incorrect (‘load’ or ‘read’ i’m not sure)