Limitation in inserting DF

[perfringo]

It's always good to read built-in help which usually contains useful information:

>>> import pandas as pd
>>> help(pd.DataFrame.iloc)
Help on property:

    Purely integer-location based indexing for selection by position.
    
    ``.iloc[]`` is primarily integer position based (from ``0`` to
    ``length-1`` of the axis), but may also be used with a boolean
    array.
    
    Allowed inputs are:
    
    - An integer, e.g. ``5``.
    - A list or array of integers, e.g. ``[4, 3, 0]``.
    - A slice object with ints, e.g. ``1:7``.
    - A boolean array.
    - A ``callable`` function with one argument (the calling Series, DataFrame
      or Panel) and that returns valid output for indexing (one of the above).
      This is useful in method chains, when you don't have a reference to the
      calling object, but would like to base your selection on some value.
    
    ``.iloc`` will raise ``IndexError`` if a requested indexer is
    out-of-bounds, except *slice* indexers which allow out-of-bounds
    indexing (this conforms with python/numpy *slice* semantics).

/..../ 

You request index which is out of bounds and documentation states that in this case .iloc will raise IndexError.