How to use two classes in DLL(COM component DLL)

[shawn1]

Rencently I need use a VIAIF.DLL to communicate with Phone. My Program screenshots is show below. Run 7 steps When the Program runs at 4~7 Steps. The Phone can't received messages by monitering with com port tool.so My question is How to use two classes in one Component DLL. In this program ,I need to use two class IViaSetup and IViaInterface. I use IViaSetup->LoadDefinition to do initialization, IViasetup->OpenCommInterface to open the Com port.Then Use IViaInterface->SendMessage to Send command to phone.Thanks

[shawn1]

Total 7 steps.When the program runs at 4~7steps,No message will send to phone by monitering the com port.