INTERPIC is the Doom 2 one still?

I created a custom intermission picture, but when I added it into my own WAD with SLADE, but it's the Doom 2 one in-game! I go to TEXTURE1, to see that the texture is the Doom 2 one. Does it have to do with a patch?

Note that I used the intermission screen as a size template, but this shouldn't be the cause because I did this with my title screen (using the Doom title screen)and that works fine.

INTERPIC isn't a texture. It's a stand-alone image, outside of markers, in the Doom Gfx format. The engine will look for a lump named INTERPIC, not a texture with that name.

Thanks! I just realized I DID put it between markers!