DOIs redirect to a generic journal page, not to article-specific pages

These DOIs (all from the same journal) redirect to a generic journal page, not to article-specific pages:

http://doi.org/10.38124/ijisrt/ijisrt24mar2109

http://doi.org/10.38124/ijisrt/ijisrt24mar1231

http://doi.org/10.38124/ijisrt/ijisrt24feb255

http://doi.org/10.38124/ijisrt/ijisrt24mar914

http://doi.org/10.38124/ijisrt/ijisrt24apr225

http://doi.org/10.38124/ijisrt/ijisrt24jun1897