This is a common thing when beginning to develop InfoPath forms for SharePoint. What you can do is go to forms management in central administration under applications administration. From here you will see a list of forms that have been deployed. Most of the time when you get the error you will see that the form you are talking about still says installing. This will not change. What you need to do is verify the forms that you are deploying with your workflow. You can check this by going to upload and then it will give you a verify button. This should tell you what you need to fix.
The problems that I ran into the most are:
1. appropriate security.
2. browser enabled.
3. the form has been published to a network location.
4. when publishing the form do not set an alternative location, leave it blank. (This one was a pain to figure out)