The input deck needs to contain the following line to assign the .op2 file used to transfer data between nastran.exe and advnlin.exe:
If you are defining the solution in NX, this line should be written automatically.
This is not the same issue. The first issue was that advnlin.op2 was not defined with an assign statment. You have apparently fixed that issue and have now proceeded further.
The current message you show indicates that the model contains a creep material (CREEP) and temperature loads, but you have not specified temperature dependent creep data (MATTC). You either need to supply temperature dependent creep data (MATTC) or remove the creep material data (CREEP).
Can you please tell me how should I specify the temperature dependent creep data (MATTC) in SOL601.
Please send me the screen shot if possible.