This form cannot be opened. It is not workflow enabled.

I'll try these things first:

1. I wont add the forms (xsn's) through central admin.
2. if i have added already, i'll will be removing it from there.
3. I'll check the install.bat and check for the form path wherever I have specified (Important):
for ex,

::"%programfiles%\common files\microsoft shared\web server extensions\12\bin\stsadm" -o verifyformtemplate -filename AssignForm.xsn

The above form "AssignForm" should be in my sharepoint workflow libraray project location.

4. I'll check for the feature.xml, the feature id should be a unique GUID & will ensure that i have these lines under the properties tag



Remember, it's *.xsn

5. I'll open the workflow.xml and check for Guid which should be unique and more importantly will check for the form urn's

6. Once i am done with all these things, i'll run the install.bat from the command prompt, Will ensure that a folder with my project library name is created under this path "C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\FEATURES\"
And the folder should hold the workflow.xml, feature.xml & all of your forms included in your install.bat.

Note: The install.bat will not spit out an error if it couldn't copy the forms. We have to ensure that the form path is right. I would suggest copying the xsn files and placing it in the project folder before running the Install.bat

Once you are done with all these, you can go to central admin->App Management->Manage Form Templates you could find your forms workflow enabled automatically.