I have 25 IgM monoclonal antibodies binding to an antigen. I confirmed that these antibodies bind to the antigen by direct ELISA. Also, i have an IgG antibody binding to the antigen.

I want to use the IgG antibody as the capture antibody and the IgM antibodies as the detection antibody in sandwich ELISA.

But, none of the IgM antibodies bind to the antigen captured by the IgG antibody. that is, i could not use the IgM antibody as the detection antibody.

Likewise, in sandwich ELISA, when polyclonal antibody against the antigen was used as capture antibody, the IgMs did not detect antigen again.

Why I might not be able to use IgM antibodies as detection antibodies.

Do you have any suggestions to use it?