Magento soap api not available special price

When getting product details with the Magento SOAP API, I can not get the special price.
I have no problems getting the price
$ price_original = $ product-> getPrice ();

The special price will be shown as zero
$ price_special = $ product-> getSepcialPrice ();

Special price is lower than the original price.
$ product-> getFinalPrice () and $ product-> getPrice () show the same value.
In the website, the special price is shown as a product price and the old price is shown with a dash. This problem only affects the SOAP API. What could be the reason why the special prize is not taken?