Type mismatch is displayed for .SET method (Blank value)

[dineshb]

Hi,
I am using QTP9.5.
I am reading blank value from MSAccess Data table (means no value in the field).
The value is assigned to a variable & then set to a text field on screen (SWING UI).

Eg

Code:

strFlightID =  arrABC(FlightID)  'value from Access data table (blank)

JavaWindow("A").JavaInternalFrame("Flight").JavaEdit("FlightField").Set(strFlightID)

During run time display following error :
Type mismatch: 'JavaWindow(...).JavaInternalFrame(...).JavaEdit(...).set'

Why the error is displayed because in text field we can enter blank value?
Is any solution on it?
Is the same issue in QTP10.0?

Thanks in advance.
Dinesh