Analog reading via bluetooth
A byte is 8 bits, it can hold a maximum value of 255.  You can not store the number 1024 in a byte.  You might want to rethink the type on ndx.
If (ndx &gt;= numChars) then why not set newData to true and print it out.  Something has gone wrong if it gets this far and you want to recover if you can.  


Apart from those minor issues your code should work as you expect it to.  Do you have a printout of what the slave's serial output was?  (What you were expecting).  Could it be something to do with the differences between SoftwareSerial and Serial?  

Edit:

I have just run a stubbed version of you code on a PC and it ran fine, so I'm going to point my finger at the SoftwareSerial link.  It could well be a misinterpretation of the interface it provides.