unexpected aliasing with cDAQ high-speed analog measurement at 102.4kS/s sample rate

[noob3]

With a cDAQ-9174 and a NI 9232, I want to measure amplitude on a signal with no frequency content above 39 kHz.  The NI 9232 max sample rate is 102.4kHz, and at that sampling rate I'd expect very little to no aliasing of my signal.  However, the attached VI appears to alias signals above a few kHz.  I've poured over the manuals and forums and watched videos without finding the information I am apparently missing.  I tried different settings in the VI, but I cannot get a different result. What am I doing wrong or misunderstanding?  Thanks.