You can receive a margin call when using a credit multiplier. This is because using credit allows you to command larger investments than your own capital will allow. You will receive a margin call once your equity (minus the multiplier) drops to 6% of the credit amount. So if you have 10k of your own capital and a 20k credit line (multiplier of 2) you will receive a margin call when your equity drops to 1200 (6% of 20k = 1200). If your equity continues to drop and reaches 3% of the credit line, in this case to 600 (3% of 20k = 600), your copied strategies will automatically be stopped and your portfolio locked.