I do not know. Is the wave file less than 3.7 mb? If it is larger than that, BB will not let it be used as a sample.
One other thing to try is to export the midi part from Beat Buddy Manager and see if there is a long amount of dead space before reaching any notes. I have that happen sometimes in Logic Pro X, if I export a midi file from its location in a song without first dragging it to the beginning of the song. If I, for example, export an 8 bar midi part that began on bar 30, Logic Pro X will automatically add 29 blank bars to the beginning of my midi file.