"directory checksum error" when attempting to install tcl

OS: HP-UX

Programs I want to install: expect and tcl

I'm lost.

I bought the book.

I began reading the book.

I want to install expect.

I've been able to download the .z, and extract it successfully.

But, of course, it apparently needs tcl and possibly tk also, and ... I am not sure about how to set all of these up together.

Also, I did attempt to extract the .gz of tcl, but I get an error: "directory checksum error" What am I doing wrong?