Did not declare IN10 which was on a car when I took van insurance, will that affect my claim?

Hi,

I got an IN10 in whilst driving my car 6/12/10. I then have had malicious damage done to my works van and am currently claiming on my insurance. I had not told them of my IN10 as it wasn't on that vehicle (and to be honest I forgot) - they are now requesting further details of it before my claim on van goes through. I havent heard anything back yet but was just wondering if they could refuse to pay out on my van?