If contains text and numbers

I have an Excel formula where I check if the value is above or below a certain threshold. My list contains both numbers and text.

Example: Column A 10 20 30 No value 40 50

I want to group all the values >=30 "Above 30",the ones between 30 and 10 "Between 30 and 10" and "No value" and 10 in "Below 10".

This is the formula that I use: =if(A1>=30,"Above 30", IF(A1<10,"Below 10","Between 30 and 10))

Everything is okay with the numbers but "No value" is marked as "Above 30".

What could be the reason for that?

Thank you!