Transfer Data from Userform to Worksheet (Invoice)

Dear all,
I'm trying to transfer values from an userform ComboBoxes, TextBoxes, etc to a worsheet to create an invoice but I don't seem to make it work properly with the following code I have.
I believe I'm almost there but somehow I cannot get it right and that's may be because I have an issue with the way the controls are formatted.
The userform in question is Stat_frm and the worksheet where it should be transferred is Inv_doc.
I'm hoping you could pinpoint where do I get things wrong or written incorrectly so it would work and do what I expect it to do.
Thank you.

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Thanks. I had to slim it down since it was both really big but also containing sensitive data. I have re-uploaded it, hopefully a clean one.
I guess the issue I have is the code you mentioned above

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but I believe I can skip the formatting and rename the STB (checkbox) to STB1-STB12.
However, where I really got stuck is with this formula

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Here what I want to achieve is to have the proper textbox number which I have to start from STM09 to get its value transferred to the worksheet.
Any help is much appreciated.

Anyone could have a look at this and provide some direction perhaps? Thank you.