Canada: Error in Tax Slips to CRA, Box 16A without Box 16

We have remitted our file to CRA and the file was not rejected, however we have been contacted by CRA to say that there are errors in the file.  CRA has said the error is in regard to an amount reporting in Box 16A (CPP2), but nothing in Box 16 (CPP).  

In our example, the employee has two tax slips for different wage loss plans.  The max CPP is deducted ($3867.50) and reported in box 16 on the LOW wage loss plan slip.  This slip reports a partial CPP2 deduction of $127.89 in box 16A.   The second tax slip for wage loss plan REG reported the remaining CPP2 deduction in Box 16A, for $60.11.  The combined deduction is $188.00 which is the correct maximum deduction.  There is nothing to report in box 16 because the employee maxed out for CPP in the first slip.