I has just made a test with the plug' in pical on minicalandar_ex, and that functions. I don't understand your problem.
There is a menu dedicated to the maintenance of the tables on piCal. Look at if it would not have an error there.
There remains however a solution to correct your problem but usable that in your precise case.
It will be necessary to modify request SQL with your values taken in phpmyadmin and the name of the file of installation of piCal.
Replace the ligne :
$sql_mid_mod = "SELECT mid FROM ".$xoopsDB->prefix('modules')." WHERE dirname = '$mydirname'";
$mcx_sql = $xoopsDB->query( "SELECT bid FROM ".$xoopsDB->prefix("newblocks")." WHERE mid=($sql_mid_mod) AND show_func='pical_minical_ex_show'" ) ;
list($bid)= $xoopsDB->fetchRow( $mcx_sql );
By :
With value_mcx equal of value numeric in pi_type. At home, I thus have mcx31… value_mcx = 31 .
In result ligne :
I hope that there that will be good.