SQL Server Update Query says table already exits

I have two tables in my database - MPRS and ALL_SSC. I want to update the ALL_SSC table with data from MPRS and in Access (where I test my SQL) it works.

However, when I run it in my VB 2010 program on the SQL Server database, it says table MPRS already exists.

I know it does! I'm not trying to create it. I'm updating FROM it... any ideas where this SQL is wrong?

SQL = "UPDATE ALL_SSC LEFT JOIN MPRS ON MPRS.MPAN = ALL_SSC.MPAN1 SET ALL_SSC.PC1 = Format([mprs].[pc],'00'), ALL_SSC.MSPCDC1 = Mid([mprs].[PC_EFD],7,4) & Mid([mprs].[PC_EFD],4,2) & Mid([mprs].[PC_EFD],1,2), ALL_SSC.MTSC1 = [mprs].[MTC], ALL_SSC.MSMCDC1 = Mid([mprs].[MTC_EFD],7,4) & Mid([mprs].[MTC_EFD],4,2) & Mid([mprs].[MTC_EFD],1,2), ALL_SSC.LLF1 = [mprs].[LLF], ALL_SSC.SUPPLIER1 = [mprs].[SUPPLIER], ALL_SSC.REGI1 = Mid([mprs].[SSD],7,4) & Mid([mprs].[SSD],4,2) & Mid([mprs].[SSD],1,2), ALL_SSC.ENG_STATUS1 = 0 WHERE (((ALL_SSC.MPAN1) Is Not Null) AND ([mprs].[ENERG_STATUS]='E'));"
cmd = New SqlCommand(sSQL, cNN)
Try
    Try
    If cNN.State <> ConnectionState.Open Then
        cNN.Open()
    End If

    Catch exCnn As Exception
    MsgBox(exCnn.Message)
    End Try
    cmd.ExecuteNonQuery()
Catch ex As Exception
    MsgBox("Cannot continue. " & ex.Message)
    Exit Sub
End Try