OneSpan SDK to retrieve

We're trying to generate the package using template. Templates are created in sandbox.esignlive.com. While generating the package we're receiving below exception, OneSpanRESTAPIHelper.OneSpanRestAPIHelperException: Error updating package with OneSpan: 400 - Bad Request - {"messageKey":"error.validation.packageActivation.unassignedRole","message":"There is a role with no signer.","code":400,"name":"Validation Error"} 


We're executing below code, 

OneSpanSDK sdk = new OneSpanSDK(); 

//step1: create a transaction out of the template OneSpanAPIObjects.Package_x pkg = new OneSpanAPIObjects.Package_x(); 
pkg.name = 'TEST'; 
pkg.description = 'TEST'; 
String placeholder1Id = 'hJNKqQncmYMQ'; 
OneSpanAPIObjects.Role role1 = new OneSpanAPIObjects.Role(); OneSpanAPIObjects.Signer signer1 = new OneSpanAPIObjects.Signer(); 
signer1.firstName = 'Mr.'; 
signer1.lastName = 'Ankit'; 
signer1.email = '[email protected]'; signer1.id = placeholder1Id; 
role1.signers = new List<OneSpanAPIObjects.Signer>{signer1}; 
String roleId = role1.Id; 
role1.id = placeholder1Id; 
pkg.roles = new List<OneSpanAPIObjects.Role>{role1}; 
pkg = sdk.helper.createPackageFromTemplate(pkg,'KpUJgwfBRmR7yX4MsMaJtRFtbzU='); 

//step2: update label fields 
OneSpanAPIObjects.Package_x pack = sdk.getPackage(pkg.id); 
Map<String, String> labelFieldValue = new Map<String, String>{ 'LjIO5N5HRJUK' => 'Ankit Thakkar' }; 
for(OneSpanAPIObjects.Document document: pack.documents){ for(OneSpanAPIObjects.Approval approval: document.approvals){ Boolean isUpdate = false; for(OneSpanAPIObjects.Field field: approval.fields){ system.debug('--> '+field.Id); if(labelFieldValue.containsKey(field.Id)){ isUpdate = true; field.value = labelFieldValue.get(field.Id); } } if(isUpdate){ sdk.updateApproval(pkg.id, document.id, approval.id, approval); } } } //step 3:send the transaction pack.status = OneSpanAPIObjects.PackageStatus.SENT; sdk.updatePackage(pack, pack.id);