Hello, welcome to the MQL5 community.
Do you have the source file or you're using the executable file (.ex5) ? It's not possible to say exactly where the problem is if we don't take a look at the code... maybe it could be a small bug, where you have the option to change lot size through an input, but programmatically the expert advisor is automatically setting the lot size.
Please provide more information so we can help you.
Thanks... I sorta figure out after a while.... It's becz of leveraging, I supposed. So, 0.01doesn't really mean 1-cent... :)
But am still confused by the margin calculation, nope, i dot have s.code.....