Selenium IDE Get Table Row Count --Perl

Hi,

I am using Selenium IDE to write few test scripts,
Now I am stuck with one problem, I am trying to get the table row count on a page, this table is a dynamic table which gets updated every time so before I fetch data from there I should know how many rows it has at that instance, I know like there can't be maximum of 30 rows per page, I tried to put the same but I get the following error message if there is no row existing "The error message is: table.rows[row]"

for(my $col=0;$col<=1;$col++)
{
for(my $row=0;$row<30;$row++)
{
if($sel->is_element_present_ok("//table[\@id='subCstTable']/tbody/tr[$row]/td")){
my $table = $sel->get_table("id=subCstTable.$row.$col");
print Dumper $table;
}
}
}

This is how I am looping and this throws an error, I kept a condition to check if data exists or not, but the command execution fails if there is no row available..Help me.