Crystal Reports help with shared variable and subreport

Message

     Hello, 

I need to pass a shared variable that gets assigned a running total  from a sub-report to the main report, and print it in the main report. 

I have this formula in the main report:

shared NumberVar x;  x

this formula is in the subreport:

shared numberVar  x := {#RG_TOTAL_GT}

However when I execute the main report I get "0.00" instead of the correct value. What am I doing wrong?