Why does not all posts show in a table?

[HelenaEA]

Hi, hope someone here can help me

I have a table, (this is just a sample, the original one is with 900 names, but otherwise similar). In the column "kursnamn" (column E) I would like to sort out a specific type of couse (course = kurs), but it does not show in the sort/selection part (I don´t know the correct term, but as you can se from the print screens, there are mors different posts in the E-column that are not shown in the sort/selection)
Why can´t I see them, and how can I do to sort out something I can´t choose from? (I hope you understand my question, I find it a bit difficult to explain those things in a foreign language...) 

[#2]

@HelenaEA Delete the first blank row and set the filter again.

[#3]

Thanks, but it doesn´t work anyway. I still dont get more to choose from in the filter

[#4]

@HelenaEA Don't understand. Row 2 is empty. When you put a filter on row 1 nothing below is picked-up. Remove the filter first. Then delete row 2 and put the filter back on row 1. Then it should work.

[#5]

Clear the filter first.
Select all edited rows and columns
Filter again

[#6]

Thank you!!!
It´s extremely strange, because this works in the sample file (that is print screened above) but not on the original one (with 900 names...)
I'll have to investigate it more - but thanks a lot so far!

[#7]

THANK YOU @Riny_van_Eekelen and @Benny_1857, I gt it now!!! (In the original file as well as the sample one) It was all the empty rows that messed it up - will NEVER use that again!