# Upconvert Signal with USRP N210 in GNU Radio Companion

I'm using a USRP N210 with this GRC diagram where I'm trying to upconvert a 1kHz sinewave.

I tried just upconverting the signal from the signal source to 2.5GHz. However, I keep getting the output signal at the frequency of the UHD:USRP Sink Block; this is, I'm not getting the sum of the baseband signal and the USRP signal as expected. What could be the reason?