Data fetched in dataframe is blank or null

## Background [Optional]
I have a copybook file like -

01 XXXXXX
04 AAAAA PIC X(10).
04 BAAAA PIC X(4).
04 CAAAA PIC X(4).
04 DAAAA PIC XX.

There is a data file (in .txt) with specified field length data. When I am trying to read it into a data frame I am just getting 1 column name XXXXXX and rows as list of actual columns. But even there the data is either null / blank
--------------------
XXXXXX
-------------------
[,,,null,]
[,,,null,]
[,,,null,]
[,,,null,]
[,,,null,]

## Question
What am I doing wrong above?