Instead of two global variables, you only need one local variable:
Set Variable [ $_date ; Company::Dt_Begin & "..." & Company::Dt_End ]
...and then simply use $_date as the Find criteria.
But if the only reason for having the two date fields is to set up the date range for the Find, then you don't need them. You could delete the Begin and End date fields and set the variable as follows:
Set Variable [ $_date ; Get ( CurrentDate ) & "..." & Get ( CurrentDate ) + 31 ]