Modules & VBA :: Form With Multi-criteria Searches / Uses Strings And Filters

I have a search form with blank fields tied to a table, four criteria search boxes, and a button to take the input from the search boxes, search the table, and populate the results on the form's blank fields. As of now, it works as long as all four criteria boxes aren't null.I used filters to achieve this, and here's the code that works as long as all four boxes are not empty. (My criteria boxes are as follows: a textbox called "Keyword" and three combo boxes called HRCombo, BuildingCombo, and RoomCombo, and the fields they're tied to are as follows: "Item Description" "HR Holder" "Building" "Room") My first line "Me.Filter = ..." was broken up to make it easier to view.

Code:

Me.Filter = "[Item Description] Like " & Chr(34) & Me.Keyword & "*" & Chr(34) & "
AND [HR Holder] = '" & Me.HRCombo & "'" & " AND [Building] = '" & Me.BuildingCombo
& "'" & " AND [Room] = '" & Me.RoomCombo & "'"
Me.FilterOn = True
Me.Requery

I need it to be able to do the search no matter which combination of criteria boxes have input. Someone recommended using if statements to do the following: Create four strings, one for each criteria box. Use 4 if statements to check if the box is null - if it is null, assign an asterisk to its string, and if its not null, assign the value I used for the above Me.Filter statement to each box's string. Then, use Me.Filter and concatenate the four strings at the end. Here's the code I used for this, and, with my limited knowledge, I can't get it to work.

Code:

Dim StrA as String, StrB as String, StrC as String, StrD as String
If Me.Keyword is null then
StrA = "*"
else
StrA = [Item Description] Like " & Chr(34) & Me.Keyword & "*" & Chr(34)
End If

[code]....