Workflow error

We are using standard AX2012 PO workflow .In this workflow working fine in one company but another company is not working and workflow is stopped .I checked with even log ,it shows following error msg

Workflow threw an exception for the following reason: There is no row at position 0. at System.Data.RBTree`1.GetNodeByIndex(Int32 userIndex)
" at Microsoft.Dynamics.AX.Framework.Workflow.Model.WorkflowModel.LoadModel(IAxClient client, SysWorkflowConfigurationData configurationData)"

I checked that user id mapeed with corresponding employee .

If you have any idea kindly share it.