Dial Soap does not cause yeast infections nor does any soap cause yeast infections.
However some soaps can cause allergic skin reactions in some people so you may get a rash from the soaps you use especially when cleaning more sensitive areas such as your Vagina or other private parts.
Or if you already have a yeast infection then the Dial Soap or any other brand of soap may cause irritation.
If you are a woman then you should avoid using any types of soap to clean inside your vagina because it can cause irritation as well as may make the yeast infection worse.
But soap itself should not cause any yeast infections.
But some people do get allergic skin reactions due to certain brands of soaps because of a skin allergy they have.