jquery show() with parameter not working in IE8

I use jQuery, .Net and IE8 as browser.

开发者_开发技巧$(".someClass").show(); 

works well, but not

$(".someClass").show("slow"); 

or

$(".someClass").show(1000);

There is no reaction at all.

Didn´t provide enough info - actually I tried to show a <td>-Tag slowly, which doesn´t work. Only show() works in connection with td´s I think.