When offering a compel, make sure that the complication is a course of action or major change in circumstance, not a denial of options.

“Oh, you’ve got sand in your eyes, so you shoot at the creature and miss,” is not a compel. It denies action rather than complicating anything.

“You know, curse your luck, I think that the sand in your eyes means you can’t really see anything. Your shots at the shoggoth go wild, puncturing a few barrels that are now gushing gasoline toward the fire pit.” This is a much better compel. It changes the scene, ratchets up the tension, and gives the players something new to think about.

For some ideas about what does and doesn’t work as a compel, check out the discussion of types of compels found in Fate Core System starting on page 72 of that book, or online at: https://fate-srd.com/fate-core/invoking-compelling-aspects#types-of-compels