When first working with Importacular, if the Start button is greyed out, you should check the following:
1) Ensure that you have activated Importacular. The screenshot below shows an instance where Importacular has not been activated (evidenced by the red link labeled "Activate Importacular" located in the center at the bottom of the screen).
If this is your issue, click on the red Activate Importacular link and use your ZeidZone credentials to activate the product.
2) Make sure that your organisation's Security Settings are not preventing you from being able to access Importacular. These will default to allow Supervisor users and the RE Security Group from the person who activated Importacular to have access to all areas. Other RE Security Groups that need access will need to be added as appropriate for your organization.
3) Make sure that you first click on your Data Source before clicking on Start. Data Sources include File as well as partners such as Classy, Qgiv, Mobilecause, etc.