Saving by Cells

try this code in a new module then assign button to it

Sub save()
Dim a As String
Dim b As String
Dim c As String
Dim d As String
a = Sheets("sheet1").Range("a1").Value 'change sheetname and or cells here
b = Sheets("sheet1").Range("b1").Value
c = Sheets("sheet1").Range("c1").Value
d = Sheets("sheet1").Range("d1").Value

ChDir _
"c:\documents and settings\martin\My Documents" 'put path here  (leave the chdir and this line out to save in curent folder)
thisfile = a & "_" & b & "_" & c & "_" & d
ActiveWorkbook.SaveAs Filename:=thisfile   
End Sub

works ok for me,see atached,
you need to save the sheet first time with the code in otherwise the variables wont populate.