Is possible to loop users balance of an existing token (user are stored in a index, they have to register).

This does not seem to work for me for some reason

function chexkIfUsersSold() external {
for(uint i = 0; i < UserInfo.length; i++){
if (UserInfo[i].registeredBalance < Token.balanceOf(UserInfo[i].userAddress)) {
UserInfo[i].hasSold = true;
}
}}