请问这个动态sql应该怎么写，

下面这个sql执行的结果总是不对，似乎因为pk的值不对，但是如果我将下面的pk=?写成死的pk='xxxxxxx'就可以，pk在数据库中的类型是字符串
Dim strSql As String
Dim conn As ADODB.Connection
Dim cmd As New ADODB.Command
Dim prm As ADODB.Parameter
mName = Me.mName
Set conn = getConnection
conn.BeginTrans
Set cmd.ActiveConnection = conn

strSql = "update Loop set name=? ,modifiedTime=?,createTime=?,pk_Project=?,description=? where pk = ?"
cmd.CommandText = strSql
Set prm = createCMDParameter(cmd, "@pk", Me.pk)
cmd.Parameters.Append prm
Set prm = createCMDParameter(cmd, "@name", Me.mName)
cmd.Parameters.Append prm

Call setParameter(cmd, "@modifiedTime", Now, adDBTime)
Call setParameter(cmd, "@createTime", Me.createTime, adDBTime)
Call setParameter(cmd, "@pk_Project", Me.pk_Project)

Set prm = createCMDParameter(cmd, "@description", Me.description)
cmd.Parameters.Append prm
cmd.Execute
conn.CommitTrans
conn.Close
Set conn = Nothing
Set cmd = Nothing
Set prm = Nothing