synchronise microcontroller and labview Visa Serial

Hi,

I have a small problem regarding my labVIEW VI. I am doing following things:

1. I am sending 7 data from microcontroller to Labview as string (ASCII characters) at a time interval of 31.45mS.
2. In labview, I read the string with delay of 32 mS.
3. I extract the individual data from string and then get the substring.
4. I use string to number converter to convert the number.
5. Finally I display the data.

The problem I am having is that when the bytes read (at Property Node) is less than 4000, the data read is perfect. But once the bytes at port reaches 4000, the data I get has periodic zeros. I think that the problem is with synchronisation of sending of data from microcontroller with the LabView. I dont know what to do with it. Could someone please advise me regarding it?

Thanks in Advance

Regards