Launch process under another user account

Question

Below is the sequence of Process calling;

1. Service calling Process A (this causes Process A to run under local system account).

2. Process A launching Process B under different user account (non admin user) using CreateProcessWithLogonW API (as logon credentials of different user is available).

3. Process B performing some activity which involves invoking another process.

Up to step 2 everything works fine. Process B launched under given user account but Process B is not able to perform a task like executing batch file or launching one more process using CreateProcess API.

Below is the code for invoking Process B;

Dim si As STARTUPINFO

Dim pi As PROCESS_INFORMATION    

Dim wUser As String

Dim wDomain As String

Dim wPassword As String

Dim wCommandLine As String

Dim wCurrentDir As String

Dim wApplicaiotnName

Dim Result As Long

si.cb = Len(si)
si.lpDesktop = "WinSta0\Default"

Result = CreateProcessWithLogonW(wUser, wDomain, wPassword, _LOGON_WITH_PROFILE, 
wApplicaiotnName, "", _CREATE_UNICODE_ENVIRONMENT, 0&, wCurrentDir, si, pi)

And below code used in Process B to execute batch file;

Dim proc As PROCESS_INFORMATION

Dim start As STARTUPINFO

Dim ret As Long

Dim lpId As Long

Dim llReturn As Long

Dim RetVal As Long

With start

    .cb = Len(start)

    .lpDesktop = "WinSta0\Default"

    If Not IsMissing(WindowStyle) Then
        .dwFlags = STARTF_USESHOWWINDOW
        .wShowWindow = WindowStyle
   End If
End With

ret& = CreateProcessA(0&, pathName, 0&, 0&, 1&, _
            NORMAL_PRIORITY_CLASS, 0&, 0&, start, proc)