AX SSRS Reports rendering issue for the first time and the same report second time it renders fine

Hi... Whenever I restart the SQL reporting services, I could not able to run any reports for first time but I can able to render the same report as second time without any issues. First time am getting below error The DefaultValue expression for the report parameter ‘AX_CompanyName’ contains an error: Request for the permission of type 'System.Security.Permissions.EnvironmentPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. (rsRuntimeErrorInExpression)" Please help...