there are reports that in some cases the IRS didn't pick up all the dependents.
I am assuming your children were under the age of 17 and they were listed on your tax return, right? (children over 16 are not eligible for the $500)
The IRS is to send you a letter within 15 days of you receiving the stimulus. suggest waiting on that letter and see what is says if you want to dispute the amount of stimulus you received.
