External DLL Issue

every time i change the Parameters that gets passed into a method inside one of our customized dll, the BPM editor thrown an error stating that it can’t find the method, and that the parameters being shown are those of the old one. another thing is why can’t i disable a bpm without it compiling the bpm i am disabling. we are upgrading from 10.1.600 to 10.2.500

BPM runtime caught an unexpected exception of ‘MissingMethodException’ type.
See more info in the Inner Exception section of Exception Details.

Exception caught in: Epicor.ServiceModel

Error Detail

Correlation ID: 27994a76-1930-418a-91b4-e219784596d3
Description: BPM runtime caught an unexpected exception of ‘MissingMethodException’ type.
See more info in the Inner Exception section of Exception Details.
Program: ERP.BpDirective.Triggers.dll
Method: A001_CustomCodeAction
Original Exception Type: MissingMethodException

Client Stack Trace

at Epicor.ServiceModel.Channels.ImplBase1.ShouldRethrowNonRetryableException(Exception ex, DataSet[] dataSets) at Ice.Proxy.BO.BpMethodImpl.Update(BpMethodDataSet ds) at Ice.Adapters.BpMethodAdapter.OnUpdate() at Ice.Lib.Framework.EpiBaseAdapter.Update() at Ice.UI.App.BpTriggerEntry.Transactions.MainTransaction.adapterUpdate() at Ice.Lib.Framework.EpiMultiViewTransaction.Update(IEnumerable1 dataSets)

Inner Exception

Method not found: ‘Void BpDirective_DD…ctor(Erp.ErpContext, Epicor.Hosting.Session, Epicor.Customization.Bpm.IBpmContext)’.