I am getting following "Error : A tree takes one root merely" when tried to display tree structure using treelib & pyodbc in python

Question

import pyodbc
from treelib import Node, Tree


try:
    tree  = Tree()
    tree1 = Tree()

    tree1.create_node("Gopalakrishnan","Gopalakrishnan")
    tree1.create_node("Vadivel", "Vadivel", parent="Gopalakrishnan")
    tree1.show()

# tree1 is working fine., below logic for tree2 is not working as expected.

    cnxn = pyodbc.connect("DSN=**;database=*;trusted_connection=yes;user=**;password=**")
    cursor = cnxn.cursor()
    cursor.execute("select distinct Sno, TreeLibCode from dbo.TreeLibTable")
    rows=cursor.fetchall()
    for row in rows:
        #tree.create_node(eval(row[1])) #eval is also not working.
        tree.create_node(row[1])
    tree.show()

except Exception as e:
    print("Error : ",e)

finally:
        cursor.close()
        cnxn.close()

result from select query:

|1 |"Gopalakrishnan", "Gopalakrishnan"

|2 |"Vadivel","Vadivel", parent="Gopalakrishnan"

output :

Gopalakrishnan

└── Vadivel

Error : A tree takes one root merely.

Output of Tree1 is fine, but Tree2 is throwing above error. Please help me in get this issue resolved.