This is Hall settling accounts with  'Screen theory'. Hall identifies the publication of C Metz's book  The Imaginary Signifier as crucial. It marked a break from what Hall calls  'semiotics one' to the later  'semiotics two'. If the first refers to the way reality is signified in language, the second conception turns, via Lacan, on the symbolic, and the de-centring of the subject. The productivity of a text includes its ability to position the viewer and so on. 

Hall's criticisms include: 

1. that there are as yet mere homologies between the Unconscious and ideology [a bit ironic, seeing that he has used this term himself to allude to relations between elements];
2. that the psychoanalytic constitution of the subject it is somehow prior, behind all the specific discourses, which dethrones the social specifics; 
3. the approach offers argument  'in general' rather than accounts of the specific modalities of the individual, despite its claims to be developing a materialism; 
4. there is no account of specific subjects and discourses -- a [general] theory of the subject is necessary but not yet sufficient [sic] (page 161). 

We can compare this criticism to Marx 's own rejection of  'production in general', in favour of analyses of  'specific modes of production and determinate conditions' (page 161). With 'Screen Theory', we can't explain the differences between patriarchies, for example or indeed the existence of specific patriarchies -- the [Lacanian] Law  is simply always patriarchal. 

Above all, there is no room for a concept of struggle in ideology. Deconstruction  unmasks specific discourses and how they work, but it does not help develop an alternative. We have a simple link to a politics of the avant-garde instead, especially in the work of Julie Kristeva [ who argued, briefly,  that language is inevitably patriarchal., so that the only escape is into experimental language, including poetry and avant-garde works of art]. 

Comments

It is worth noting that the Media Group at the Birmingham Centre spent a whole year, 1977-8, in grasping and refuting  'Screen Theory' , which gives some indication of the relative priorities of theoretical and political work! 

Secondly, although Hall is condemning general theory among Lacanians, and what it became known later as  'foundationalism', his own alternative gets very close to seeing  'struggle' as some essential foundation. 

Finally, it is interesting for me to re- read this article, because in the process I have become aware that I might have misunderstood the difference between  'semiotics one' and 'semiotics two' (unless it is incoherent. of course!). I had taken this to mean a more general shift in the interests of semioticians, away from analysing the structures of ideologies [which kept them as allies for marxists and feminists] , towards a more general interest in the processes at work in any utterances [which turned into a deconstruction of marxisms and feminisms too, most spectacularly in 'postmodernism'].

Now have a look at a 'Screen Theory' attack on Hall et al? [here]