Slow Query Using A Global Variable

Hello,

I have the following query that I set up as a test, and it runs fine:

SELECT STATUSHISTORIE.*
FROM STATUSHISTORIE LEFT JOIN PROBLEM_DE ON STATUSHISTORIE.PROBLEM_ID = PROBLEM_DE.PROBLEMNR
WHERE (((STATUSHISTORIE.STATUSDATUM)<#1/1/2005#) AND ((PROBLEM_DE.DATENBEREICH)='SPMO') AND (((Left(([PROBLEM_DE].[MODULZUORDNUNG]),InStr([PROBLEM_DE].[MODULZUORDNUNG],"-")-2)))='K29') AND ((PROBLEM_DE.ERLSTAND)<>"WEIF"))
ORDER BY STATUSHISTORIE.PROBLEM_ID,
STATUSHISTORIE.STATUSDATUM;

I then set up two global variables ( a String and a Date) and respective functions to return them – ReturnE( ) and ReturnKW( ). Now my query looks like this, but takes ages to run:

SELECT STATUSHISTORIE.*
FROM STATUSHISTORIE LEFT JOIN PROBLEM_DE ON [STATUSHISTORIE].[PROBLEM_ID]=[ PROBLEM_DE].[PROBLEMNR]
WHERE (((STATUSHISTORIE.STATUSDATUM)<ReturnKW( ) ) AND ((PROBLEM_DE.DATENBEREICH)='SPMO') AND (((Left(([PROBLEM_DE].[MODULZUORDNUNG]),InStr([PROBLEM_DE].[MODULZUORDNUNG],"-")-2)))=ReturnE( ) ) AND ((PROBLEM_DE.ERLSTAND)<>"WEIF"))
ORDER BY [STATUSHISTORIE].[PROBLEM_ID], [STATUSHISTORIE].[STATUSDATUM];

My two public functions that return the global variables look like this:

Public gstrE As String 'global variable: contains E used for query
Public gdatKW As Date

Public Function ReturnE ()
ReturnE = gstrE
End Function

Public Function ReturnKW ()
ReturnKW = gdatKW
End Function


The tables are actually Views set up from an ODBC Data source. Can anyone please tell me why these global variables are causing the traffic jam? :)

Thanks in advance
J