I am simulating a problem based on RC phase shift oscillator based on Opamp from a textbook. I have included the ua741 subcircuit and also added oscad libraries to \r\nit. It shows the following on the ngspice terminal window, i does not getting result, it is showing that

Error: Could not find Include file vplot8_1.sub

I have tried unmark the option "Prefix references 'U' and 'IC' with 'X'". I tried in both ways still not getting result