LabVIEW

Print size for label printer Brother PT-P750W

Hi everyone,

I'm fairly new to LabVIEW.
I've been trying to print labels by sending visible front panel to a Brother PT-P750W through USB with mixed result. It can print fine but the problem is labview never updates the paper size of his file. (see 9mm.png and 9mm_2.png).
I already used another printer which is the Brother PT-P710BT and this problem doesn't occur when i change the printing size. (see 12mm.png and 24mm.png, I didn't change the size in the printer so that you could see the difference because it would then print and no message would show up)
To be able to print correctly (not considering layout of front panel, just the act of printing) i need 2 things : The printer settings set to the correct size and having the correct size physically in the printer. As i have no control over the paper size programmatically i assumed it was made automatically by LabVIEW because it worked like that with the PT-P710BT.
I have attached my 2 vis.

ihm_imprimantes let you choose the printer and the size of the labels. The label size is saved in an FGV to be used later in the second vi Print_Encode.vi.
Print_Encode.vi will process the data received to make a front panel that will suit my needs. It will also send cmd command to change the printer settings (see folder Printer_settings along with the label on Print_Encode.vi's diagram to put the folder in the correct spot).
I've checked .net assembly without any success.

So my question is why is labview not updating his paper file size ?
Is there a way to force it programmatically?

Any help would be wonderful,
Thanks,
Tommy