DVM205AM and frequency

I have tried to measure en 1 kHz tone coming from my smartphone jack but it told me that it was 25 Hz.

What is the conditions for measuring frequency with the DVM205AM?

Best regards
Hugo

Please: Velleman Projects items only (see forum rules).
For all other items of the Velleman group, please use the online support form:
http://www.velleman.eu/support/contact/?product=351256