Error starting a wf from the item menu

Hi,

 I have created two list workflows and I've set them to allow user to start them from the item menu. I've also created a custom action for the menu with SharePoint Designer to open directly a form of a related item, so in my item menu I have from the top: Custom Action, Workflow 1, Workflow 2.

 If I try to start Workflow 1 from the menu, everything is ok, but if I try to start Workflow 2, it errors saying that a previous workflow of the same type is already running on that item (and I'm sure it's not true).

If I try to start them from the workflow page, they start with no problem.

Anyone has bumped into the same problem?

Thanks

 Giacomo