THETA numbering

Dear all, When trying to execute a rather complex control stream with many THETAs, I get the following error message from NMTRAN (see below). I tried to use a different number (e.g. 111) but the error persists. It seems as if NONMEM does not accept 3 digit subscripts? Has anyone had a similar problem? Thanks, Andreas. PS: I'm using NM 7.2. NM-TRAN MESSAGES AN ERROR WAS FOUND IN THE CONTROL STATEMENTS. AN ERROR WAS FOUND ON LINE 169 AT THE APPROXIMATE POSITION NOTED: S13_3 = THETA(100) X 484 SUBSCRIPT MUST BE AN INTEGER CONSTANT. Andreas Lindauer, Ph.D. Associate Principal Scientist, Clinical PKPD Pharmacokinetics, Pharmacodynamics, and Drug Metabolism Merck & Co. / MSD Notice: This e-mail message, together with any attachments, contains information of Merck & Co., Inc. (One Merck Drive, Whitehouse Station, New Jersey, USA 08889), and/or its affiliates Direct contact information for affiliates is available at http://www.merck.com/contact/contacts.html) that may be confidential, proprietary copyrighted and/or legally privileged. It is intended solely for the use of the individual or entity named on this message. If you are not the intended recipient, and have received this message in error, please notify us immediately by reply e-mail and then delete it from your system.