Oh, I understand the cause. You took a voltage source (V) and changed it symbol name to B. Therefore, the so called B1 source in your schematic is actually a voltage source.
V is Voltage Source
B is Behavioral Voltage Source
They are two completely different thing in spice. Goto Help to get more information.
Behavioral Voltage Source support functions and operators.
I continue learning. I think learning to simulate correctly is not easy. I greatly appreciate the effort that very experienced people altruistically offer their time and knowledge to teach us.