VBA Userform Data Entry - Reference Number problem

Hi Guys,

Me again and I have another problem I cannot seem to work my way around.

I have a userform that will allow the user to enter in new data, however, the first column in the sheet where the data is contains reference numbers.

I need the userform entry TextBox1 to be last reference number in the sheet +1 so that each new entry gets the next reference number in the line.

So Column A Row 2 has the reference TestRef1, I need the userform to state in TextBox1: TestRef2 and so on...

Please help me as this is for a project that I am working on.

Thanks!