I recently purchased a DSC1616 and it is working except for the siren. When I hook up the internal siren it works fine but when I hook up the Doberman it lets out this low tone constant noise as if it is receiving enough voltage to work but not go off. I even unhooked the inside speaker and only connected the Doberman and it does the same thing. It is like some sort of background interference in the line. Has anyone seen anything like this before?