I would like to discuss several experiments we did together with my present and former MA students from St.Petersburg State University. Much work has been devoted to number attraction errors in subject-verb agreement (e.g. "*The key to the cabinets were rusty"). Among other things, it was noted that: (i) only plural attractors cause a significant effect; (ii) in languages with morphological case, attraction is much stronger when the form of the attractor coincides with nominative plural (e.g. Hartsuiker et al. 2003). I will show that singulars can cause attraction too – if they look like Nom.Pl forms. Gen.Sg forms of some Russian nouns coincide with Nom.Pl (and Acc.Pl) forms: e.g. vecherinki from vecherinka ‘party' and trigger stronger effects than genuine plurals both in production and in comprehension. Then I will show some data from case attraction where form ambiguity also plays a crucial role and discuss the implications for the models of attraction and beyond.