Strange error with SMSsim constant

Hello All,

I need to access data on a phone sim. I am using code direct from WX help as below;\
=============================================
// Number of SMSs stored on the SIM card
STC_NbSMS = "You have " + SMSNbMessage(smsSIM) + " messages."

// Read the first SMS stored on the SIM card
ResRead is boolean = SMSFirst(smsSIM)

WHILE ResRead = True
// Display the characteristics of this SMS in a table :
// the SMS variable is automatically updated
TableAddLine(TABLE_SMSTable, SMS.Subscript, SMS.Message, SMS.Number, SMS.ReceiveDate)
// Read the other SMSs
ResRead = SMSNext(smsSIM)
END
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The challenge I have is when I use ResRead = SMSNext(smsSIM) WM complains smsSIM is not a valid command. [though ResRead = SMSNext(smsMemory) works fine]. I am just wondering if anybody has encountered this problem before and how you solved it.

Thanks

Sam