incident customerid to custom task customers

I tried creating a new entity reference, but it is always blank.  I also tried the following code, but I get an object error now.

                        if (localContext.PreImage.GetAttributeValue<EntityReference>("customerid").LogicalName != null)
                        {
                            Guid tmpCustomerGuid= localContext.PreImage.GetAttributeValue<EntityReference>("customerid").Id;
                            tmpCustomerObject = new EntityReference("Account",tmpCustomerGuid);

                        }

The fields are populated as I made the mandatory on the form. 

Any help would be appreciated.