Combine a formula from texts in different cells by VBA

I would like a macro to create a cell containing a formula like:

='X:\Documents\Database\Database files[DatafileB.xlsm]computed'!A3

(as is visible in the example picture and xlsx file: )
MacroCombineValuesFormula.jpg

So that this cell uses the values of:

Cell B1: The indicated cell (in this example: A3)
Cell B2: The indicated tab (in this example: computed)
Cell B3: The indicated xlsm-file name (in this example: DatabasefileB.xlsm)
Cell B4: The indicated file path (in this example: X:\Documents\Database\Database files)
How can I make a macro that creates that formula in cell B5?

I know I can make that formula by concatenate or using the & signs, but then it just sees it as a text and not the formula that does the desired job.

Thanks in advance.



Regards, Kenny