Subtracting two waveforms, one aquired using DAQ analog voltage input, and the other one being internally generated

Hello NI Community,
I am new to LabView and was hoping someone might be able to help with a question I have. Right now, I am using a DAQ unit to sample an externally generated sinusoid and I would like to alter that signal by adding to it another signal that I could control using the front panel. Whenever I try to just connect the input with something like the sine waveform vi and put a subtraction sign between them it doesn't work (I get an empty waveform graph). To get around this, I have resorted to sending out a signal (through an analog output) and then reading the signal on the Daq, and then finally I add the two together. Doing it that way works, but it wastes two channels and I imagine there is a better way. I have attached my VI, and I labelled the location of interest  "Where the Signals Get Subtracted", which is currently shown using the two inputs.
Thanks,
Leo

What a mess.  I have no idea where you are trying to do the subtraction.  Can you make a very small VI (one whose Block Diagram fits on a single screen) that shows what you are trying to do?  Include the Sine Wave Generator, and you can include a "Black Box" that says "From DAQ".  But thank you, at least, for posting code, not a picture.
Here's a suggestion that may help make things less messy -- do you know about the Diagram Cleanup tool?  See the icons at the top?  The right-most one looks like a broom next to a VI.  Save your VI first (in case you don't like what it does), Select All (Ctrl-A), then click this button -- you may like the result.
Bob Schor

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