Superfish problem

Superfish problem

Hello,
I have a problem with my Superfish menu. My menu structure is
Cat1
      |_Subcat11
      |_Subcat12
Cat2
      |_Subcat21
      |_Subcat22
            |_Subcat221
            |_Subcat222
            |_Subcat223
            |_Subcat224
            |_Subcat225
            |_Subcat226
            |_Subcat227
            |_Subcat228

The problem I face is that only the first 5 items of the submenu are visible. can anyone help?

thanks