If your credit card is declined, first try clearing your browsers cache and cookies; then add a new CC profile during the check out process and re-enter your CC information.
Here are some other things to check...
*Have you entered a Default Billing/Shipping Address to your account? This must be done to avoid this error.
*Does your address in your profile match the address on your credit card?
*Does your name match the name on the Credit Card?
*Please make sure there are no special characters (IE: ', ~, `) in your name or address in your account.
*This could be an issue with your anti-virus or firewall blocking the Daz 3D website. Please try disabling your firewall and see if the results differ.
*You can also try running your browser as administrator. To do this, right click on the launch icon and choose Run as Administrator.
If you feel all of these things are correct, and you have enough funds for your purchase, you may contact our sales department for more trouble shooting. https://www.daz3d.com/help/help-contact-us