chain manipulation – StringJoin Error in the implementation of the BSM model

I came across the world of Mathematica and FeynRule recently and I try to implement a Lagrangian that includes the Top Partner (BSM) fields in addition to the Standard Model. In the process, everything worked fine until I found the error when creating UFO files for MG5.

StringJoin :: string: string expected at position 2 in P. <> CreateObjectParticleName[PartNameMG[Overscript[topT, -]]].
StringJoin :: string: string expected at position 2 in P. <> CreateObjectParticleName[PartNameMG[Overscript[topT, -]]].
StringJoin :: string: string expected at position 2 in P. <> CreateObjectParticleName[PartNameMG[topT]].
General :: stop: The additional output of StringJoin :: string will be suppressed during this calculation.

In this error message, I understand that in the process of creating the Python files that can be used for MG5, Mathematica can not convert the top T (in my case, one of the main partner fields) into a string. I would like to know how to solve this problem. I tried running MG5 with this UFO output file, but immediately complained that the previous line gives a syntax error in the vertices.py file. I would really appreciate if someone could help me.

For additional information, I am using Mathematica version 11.3.0.0 and FeynRule version 2.3.32.

Warning: Non-positive QED interaction order.

I also get this error at the end, even if I set M $ InteractionOrderLimit to be less than equal to 99 for QED and QCD.