validation error: <img> escaping malformed URI reference

I'm trying to set up a fully tokenized email template. But I've gotten several validation errors that won't let me save - metatags, some proprietary attributes, etc.

I've sacrificed these to complete my task, but one remains: Validation refuses to accept a tokenized image url. I've tried different html type attribute tags, hoping that would solve it, but no luck. I always get the error: Warning: <img> escaping malformed URI reference

I've tried my urls three different ways:

entire url:

<img src="{{my.Content - EM_Header image}}" alt="xxxx" Title="xxxx" border="0"/>

including http:

<img src="go.idt911.com/rs/000-XXX-000/images/{{my.Content - EM_Header image}}" alt="xxxx" Title="xxxx" border="0"/>

replacing characters with unicode:

<img src="http://go.idt911.com/rs/746-PTV-801/images/{{my.Content - EM_Header image}}" alt="IDT911" Title="IDT911" border="0"/>

Any thoughts?