AmazonMetaData Unable to cast object of type System.String

Question

Unable to cast object of type 'System.String' to type 'System.Object[]'

here is the code:

string str = MFI.Helpers.Helpers.AmazonS3ImageURLGet(userType, id, pictureFile);
            AmazonMetaData amazonMetaData;
            if (MFI.Helpers.Helpers.processingImages.GetObject(str) != null)
            {


                //amazonMetaData = (AmazonMetaData)((object[])MFI.Helpers.Helpers.processingImages.GetObject(str))[0];
                amazonMetaData = (AmazonMetaData)((object[])MFI.Helpers.Helpers.processingImages.GetObject(str))[0];

            }

error in amazonMetaData = (AmazonMetaData)((object[])MFI.Helpers.Helpers.processingImages.GetObject(str))[0]; 

 

how to solve??