Thank you for your post. Of course I used -l <filename>. The data you asked for:
Linux kernel 2.6.21.5, Slackware 12.0 (mostly or all GNU). Spin I guess is the version.
However, I found this, assembling with 2.09.09 (may be 2.03.01, the previous version I had, has identical behavior): After having fixed the last two errors displayed, a new compilation threw a lot more errors. Quite understandable for a one pass assembler. But, alas, a listing file was now output. This is quite another thing. But the listing does not show any errors.
As I was writing a new post arrived: Yes, I had a lot of "parser: instruction expected" but no listing. And I used lower 'L' (-l <filename).