SP2022 Picatinny Rail + Surefire Question

[unltd]

Hi all. I have an SP2022 and I just bought a surefire x300. I can't seem to fit it on right. I can slide it on the rail but not far enough for it to click into place, because I can easily tug it off. Is the rail too short?

PS I swapped the x300 mounting plates so I have the Picatinny adapter on for sure.

Thanks in advance for any help.