My proposal tells me that the opportunity is now unavailable.
When I look at my proposal in the list, it shows the 
icon (expired/unavailable opportunity). But this doesn't make any sense to me, as I was just working on it.
There are two "common" possibilities for this:
1. This opportunity has been removed from grants.gov, and any submission under this FOA will not be successful. See here for instructions in our users manual how to search for your opportunity under the opportunity tab of Cayuse424.
2. This opportunity may have been recently updated by the funding agency, and changes made to the opportunity mean that it cannot be submitted in its current form. Fortunately, Cayuse424 has a convenient feature called "transformation" allowing your data already entered to be reloaded under the most recent version of the opportunity forms for that opportunity number. Note that in some cases, the opportunity number will be different. Click here for instructions on how to transform a proposal.