Black Pixels Disappear When I Move Them

As the title says, when I select black pixels and then move them, they just vanish.

I’m currently working on weapon animation, but can’t actually work on the gun itself.

Here’s a photo of what it looks like, (can’t post a before/after because I’m new to the community) any help would be greatly appreciated:

image

Make sure this setting on the marquee tool is set to mask, and not to your black color

If that doesn’t solve it, please post a screenshot of your entire program with the marquee tool selected.

Yes!
That worked!

Many thanks!