Ontario Highway Traffic Act

Hope someone can offer some insight on this one.

Recently got a ticket for Passing Off Roadway as per HTA Sec. 150 (2). Here's how it happened:

I was coming off HWY 400 onto HWY 401 East bound. The traffic on the on ramp was crawling along. When we got close to the end of the on ramp where the solid white line ends, I switched lanes to the left ...