[TxMt] Mail-Markdown-HTML-Mail error

I thought this workflow should work, but it’s running into trouble:

I open a new message in Apple Mail. I type the keyboard command for Edit in TextMate. I write a simple document in Markdown. I use the Markdown bundle command to convert to HTML. I use the Mail bundle command Send HTML as email via mail. I get “Syntax Error: Expected end of line but found property (-2741)"

Problem seems to occur whatever the language grammar is set to. I’m using TM version 1.5.9, with updated bundles. I didn’t find a mention of this in the archive.

Thanks very much for any suggestions about a fix or a better workflow.