I was 61 when I had surgery. I was in good shape as I have consistently lifted weights and exercised my entire life. Despite that, after surgery I was completely incontinent. No matter how many Keegles I did, it did not work. I ended up trying everything, clamps, condom catheter, different exercises, etc. I was producing an overwhelming amount of urine, filling my condom catheter bag many times over the course of a day. I also had a lot of pain. Part of my problem was that I had an infection that nobody thought was there as they all said it was just part of healing. After I demanded to have tests for infection (which proved that I was indeed dealing with a serious infection) I was out on antibiotics (like 6 weeks after surgery) my ability to control urine returned quickly.
If you have an issue with not being able to contract your muscles for Keegles, do different exercises. I have read research articles that show that there are several exercises that far exceed the effectiveness of Keegles for strengthening the pelvic floor.
I would make sure my bladder was empty. Put on a fresh Depends. Put a towel on the floor and do bridges, side leg raises, cat-cows, unweighted squats, sit ups, crunches, all fours hovering, leg lifts, pelvic thrusts, things like that. Do them every day. I stopped with Keegles because when you do larger muscle group movements, you are exercising those muscles as part of the larger group.
If none of those are possible, try to work on the exercise you can almost do the best and practice that and add as you increase strength.
Talk to your doctor and seek help from a physical therapist if possible.
My incontinence resolved. I returned to pre-surgery control after about 6 months. However, I worked on it every day.
Good luck!