What is the BIGGEST mistake made in marketing?

Source melissadata.com

Following Up On Customers, by Jeffrey Dobkin

What is the BIGGEST mistake made in marketing? This mistake is made by 99% of the companies marketing products or services… The biggest mistake in marketing - and not just direct marketing, but any marketing - is made by people who spend a lot of time, energy, and money on an ad or an inquiry-generation program. When they receive the highly qualified lead it brings in, they send a brochure and a letter. At best, they call about a week later. When a sale is not immediate, they hang up, and they never call back or send another letter. They assume their campaign failed. What a mistake. A single letter and brochure is not a campaign. A campaign is not a single effort of anything - why do you think they call it a campaign? A campaign is a sustained effort over time…. The biggest mistake made in marketing is not contacting a well-qualified buyer, who has expressed an interest in your product or service after the first mailing, a second time with harder-hitting additional marketing material or letters.