Identical random number in a for loop, delayed expansion not working?

This for loop only produces identical random values. Every other problem about this I've come across is solved by setlocal EnableDelayedExpansion but mine is already using it. What could be wrong?

setlocal EnableDelayedExpansion
for /l %%n in (1 1 10) do (
    set /a randomnumber=!random!*total/32768+1
    for /f "tokens=1* delims=:" %%a in ('findstr "^%randomnumber%:" list.txt') do echo %%b >>list2
)