Sounds like you're using the VC.bat file that comes with DSD+. That bat file has -rv (DSD+ role is trunked voice follower) in it. But you're just feeding DSD+ from a tapped scanner, correct? So there is no voice following going on (that requires that DSD+ be paired with a version of FMP). DSD+ is even warning you that by using -rv, you've implied that FMP is the audio source, which will disable auto polarity detection and that's a very bad thing to do when using a tapped scanner.
The four batch files are for running a full trunk following setup. If you're just using a single copy of DSD+ with a tapped scanner, you really should create and use your own batch file.
Since the inputs and outputs you want to use are both 1, and 1 is the default, you don't need any command line parameters to run DSD+. You could just double click on DSDPlus.exe and away you go. If you don't get good decoding, the signal is weak/bad or your tap is no good. What does the audio waveform look like during an active call or while parked on a control channel? Post a screen grab or some recorded raw audio.