soldering onto VIAs

[chelfyn]

I'm mid-way through a MARS2 chip installation, and all's been going well until I had to try and solder directly onto the VIAs on the back of the board.... I've tried shadowknytes tips and tricks, but I can't get the VIA's to take any solder.

I'm on the verge of admitting defeat! Can anyone help with info on how to make these connections....