Can’t get older cat to use microchip flap

[Gingerbread981]

I got a pet safe cat flap fitted to stop the neighbours cat coming in.
my bigger cat gets in and out.
my skinnier cat goes out but stays out. This is going to become more of a problem in winter etc.
Her chip is paired up etc. I’ve tried treats, popping her through etc. I’ve put a little step outside incase it’s the height.
She was outside wet this morning, no idea how long she’d been out.
any suggestions?

I used a clothes peg on the side of the flap part to keep it partially open, gradually moving it lower down si that the "opening" became smaller and left treats on either side. It took him about 2 weeks to fully get the hang of it!

Train her to recognize the hole on the way back by having it open in good weather while you watch and reward her. Your cue can be calling her name while she is out with a treat in your hand she can see through the hatches