Maybe it´s a silly question, but I´m having some trouble to validate a NULL value. I´m taking data from a Excel Worksheet, don´t knowing how large is it. So, I need to break my DO WHILE when the program finds a blank cell. My code is something like this.

	DO WHILE .T.
		micontrol = .cells(lnfila,2).VALUE
		IF micontrol = .null. then
			EXIT
		ENDIF
                *....
                *Some code that works fine...
                *....
        ENDDO

Everything works fine, but I never can reach EXIT, and the other code continue excuting, logically sending me an error. Using the debugger, the value for micontrol is .NULL.

What's wrong??

Thanks in advance!