The entity is read-only

I am currently developing an app with the .net sdk and am trying to input a sales invoice. All seems well until I call the .Save() method on my invoice. I get the error that the entity is read only. Based on a previous search through the forum, If I go to Help -> About Sage Accounting, the Plan Level is Expired. My question is, is this causing the read only error? I purchased the product and have a serial number and activation key. Do I also need to purchase a plan? I'll only need to use this sage install for development, probably the next couple of weeks...

Any help would be appreciated. Thanks!

  • Update. I was able to get the Plan Level changed but it's still throwing the same exception when I try and save the invoice, that the entity is read only. When creating the invoice, the property IsSaveAllowed is set to false. Could this be causing the issue?