Comparing values after ChangeType not working

I have the problem, that comparing values after changing the type (in this case to int) does not work:

In my point of view (see the debugger), _pkValue and _defaultValue are both integers with the same value.

The problem is, that the if-statement should not be entered, because both values are 0.

I'm sure it is a very simple thing, but i can't figure it out.

EDIT: Code

object pkVal = pks.First().Value.GetValue(this, null);

if (pkVal != null)
{
    var defaultValue = TypeHelper.GetDefaultValue(pkVal.GetType());

    var _pkValue = Convert.ChangeType(pkVal, pkVal.GetType());
    var _defaultValue = Convert.ChangeType(defaultValue, pkVal.GetType());

    if (_pkValue != _defaultValue)
    {
        canset = false;
    }
}

Thank you!