My schematic in PLECS Blockset is not opening

I have developed a model in PLECS Blockset, saved the file and closed it. When I came back to continue working on it, the PLECS circuit is now empty. I get the following error from PLECS Blockset when I open the Simulink model.

Model string, line 3359: syntax error before ‘’

Could not find schematic ‘filename here’ in string.

Hello,

To make sure this isn’t a license issue, please verify if you have a valid license. Go to the yellow PLECS model window, then click on Help -> PLECS License Manager -> Manage license files… You should see a license.lic file here.

If you also see a viewer license, remove this as stated here – https://www.plexim.com/support/solutions/1008.

Regards,Manu